Thyroid nodule pathophysiology: Difference between revisions

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==Overview==
==Overview==
[Pathogen name] is usually transmitted via the [transmission route] route to the human host.
Thyroid nodules may arise from different [[Cells (biology)|cells]] in the [[thyroid]] parenchyma. The [[pathogenesis]] of developing a thyroid nodule may differ based on the type of the [[nodule]], and whether it is [[malignant]] or [[benign]]. Basically thyroid nodules may develop secondary to [[hyperplasia]], [[mutations]] and resultant [[carcinoma]], excess [[colloid]] accumulation, or from[[inflammation]] of [[Thyroid gland|thyroid tissue]]. [[Genetic mutation]] is considered as one of the most important mechanisms of developing thyroid nodules, especially [[Thyroid Cancer|neoplastic thyroid nodules]]. Most of these [[mutations]] occur as [[Somatic mutation|somatic mutations]], while some may exhibit familial inheritance. The most important variety of familial [[thyroid cancers]] are caused by [[genetic mutations]], and are called familial non-[[medullary thyroid cancer]] (FNMTC). Other important [[genes]] related to thyroid nodule formation include, N&H ras, RET, Gsp, C-MET, TRK, EGF / [[EGFR|EGF-R]], and [[P53 gene|P53]].  
Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
[Disease name] is transmitted in [mode of genetic transmission] pattern.
[Disease/malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
Development of [disease name] is the result from multiple genetic mutations.
Genes involved in the pathogenesis of [disease name] include [gene1], [gene2], and [gene3].
The progression to [disease name] usually involves the [molecular pathway].
The pathophysiology of [disease name] depends on the histological subtype.
==Pathogenesis==
==Pathogenesis==
A summary of [[Thyroid Gland|thyroid]] nodule pathophysiology is presented in the slides below:
{{#widget:ThyroidNodulePatho}}
<ref name="pmid3755697">{{cite journal |vauthors=Aozasa K, Inoue A, Katagiri S, Matsuzuka F, Katayama S, Yonezawa T |title=Plasmacytoma and follicular lymphoma in a case of Hashimoto's thyroiditis |journal=Histopathology |volume=10 |issue=7 |pages=735–40 |year=1986 |pmid=3755697 |doi= |url=}}</ref><ref name="pmid862558">{{cite journal |vauthors=Bastomsky CH |title=Enhanced thyroxine metabolism and high uptake goiters in rats after a single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin |journal=Endocrinology |volume=101 |issue=1 |pages=292–6 |year=1977 |pmid=862558 |doi=10.1210/endo-101-1-292 |url=}}</ref><ref name="pmid8612537">{{cite journal |vauthors=Brix K, Lemansky P, Herzog V |title=Evidence for extracellularly acting cathepsins mediating thyroid hormone liberation in thyroid epithelial cells |journal=Endocrinology |volume=137 |issue=5 |pages=1963–74 |year=1996 |pmid=8612537 |doi=10.1210/endo.137.5.8612537 |url=}}</ref><ref name="pmid8608777">{{cite journal |vauthors=Burch HB |title=Evaluation and management of the solid thyroid nodule |journal=Endocrinol. Metab. Clin. North Am. |volume=24 |issue=4 |pages=663–710 |year=1995 |pmid=8608777 |doi= |url=}}</ref><ref name="pmid2627756">{{cite journal |vauthors=Coclet J, Foureau F, Ketelbant P, Galand P, Dumont JE |title=Cell population kinetics in dog and human adult thyroid |journal=Clin. Endocrinol. (Oxf) |volume=31 |issue=6 |pages=655–65 |year=1989 |pmid=2627756 |doi= |url=}}</ref><ref name="pmid2196027">{{cite journal |vauthors=de los Santos ET, Keyhani-Rofagha S, Cunningham JJ, Mazzaferri EL |title=Cystic thyroid nodules. The dilemma of malignant lesions |journal=Arch. Intern. Med. |volume=150 |issue=7 |pages=1422–7 |year=1990 |pmid=2196027 |doi= |url=}}</ref><ref name="pmid2164546">{{cite journal |vauthors=Di Carlo A, Mariano A, Pisano G, Parmeggiani U, Beguinot L, Macchia V |title=Epidermal growth factor receptor and thyrotropin response in human thyroid tissues |journal=J. Endocrinol. Invest. |volume=13 |issue=4 |pages=293–9 |year=1990 |pmid=2164546 |doi=10.1007/BF03349565 |url=}}</ref><ref name="pmid1661579">{{cite journal |vauthors=Dumont JE, Maenhaut C, Pirson I, Baptist M, Roger PP |title=Growth factors controlling the thyroid gland |journal=Baillieres Clin. Endocrinol. Metab. |volume=5 |issue=4 |pages=727–54 |year=1991 |pmid=1661579 |doi= |url=}}</ref><ref name="pmid7920658">{{cite journal |vauthors=Duprez L, Parma J, Van Sande J, Allgeier A, Leclère J, Schvartz C, Delisle MJ, Decoulx M, Orgiazzi J, Dumont J |title=Germline mutations in the thyrotropin receptor gene cause non-autoimmune autosomal dominant hyperthyroidism |journal=Nat. Genet. |volume=7 |issue=3 |pages=396–401 |year=1994 |pmid=7920658 |doi=10.1038/ng0794-396 |url=}}</ref><ref name="pmid1995765">{{cite journal |vauthors=Ericsson UB, Lindgärde F |title=Effects of cigarette smoking on thyroid function and the prevalence of goitre, thyrotoxicosis and autoimmune thyroiditis |journal=J. Intern. Med. |volume=229 |issue=1 |pages=67–71 |year=1991 |pmid=1995765 |doi= |url=}}</ref><ref name="pmid8026388">{{cite journal |vauthors=Farid NR, Shi Y, Zou M |title=Molecular basis of thyroid cancer |journal=Endocr. Rev. |volume=15 |issue=2 |pages=202–32 |year=1994 |pmid=8026388 |doi=10.1210/edrv-15-2-202 |url=}}</ref><ref name="pmid11172729">{{cite journal |vauthors=Liekens S, De Clercq E, Neyts J |title=Angiogenesis: regulators and clinical applications |journal=Biochem. Pharmacol. |volume=61 |issue=3 |pages=253–70 |year=2001 |pmid=11172729 |doi= |url=}}</ref><ref name="pmid7714083">{{cite journal |vauthors=Gaitan E, Cooksey RC, Legan J, Lindsay RH |title=Antithyroid effects in vivo and in vitro of vitexin: a C-glucosylflavone in millet |journal=J. Clin. Endocrinol. Metab. |volume=80 |issue=4 |pages=1144–7 |year=1995 |pmid=7714083 |doi=10.1210/jcem.80.4.7714083 |url=}}</ref><ref name="pmid1356609">{{cite journal |vauthors=Gaskin D, Parai SK, Parai MR |title=Hashimoto's thyroiditis with medullary carcinoma |journal=Can J Surg |volume=35 |issue=5 |pages=528–30 |year=1992 |pmid=1356609 |doi= |url=}}</ref><ref name="pmid7988459">{{cite journal |vauthors=Gerber H, Huber G, Peter HJ, Kämpf J, Lemarchand-Beraud T, Fragu P, Stocker R |title=Transformation of normal thyroids into colloid goiters in rats and mice by diphenylthiohydantoin |journal=Endocrinology |volume=135 |issue=6 |pages=2688–99 |year=1994 |pmid=7988459 |doi=10.1210/endo.135.6.7988459 |url=}}</ref><ref name="pmid21190442">{{cite journal |vauthors=Wang CC, Friedman L, Kennedy GC, Wang H, Kebebew E, Steward DL, Zeiger MA, Westra WH, Wang Y, Khanafshar E, Fellegara G, Rosai J, Livolsi V, Lanman RB |title=A large multicenter correlation study of thyroid nodule cytopathology and histopathology |journal=Thyroid |volume=21 |issue=3 |pages=243–51 |year=2011 |pmid=21190442 |pmc=3698689 |doi=10.1089/thy.2010.0243 |url=}}</ref><ref name="pmid9429860">{{cite journal |vauthors=Gharib H |title=Changing concepts in the diagnosis and management of thyroid nodules |journal=Endocrinol. Metab. Clin. North Am. |volume=26 |issue=4 |pages=777–800 |year=1997 |pmid=9429860 |doi= |url=}}</ref><ref name="pmid9020075">{{cite journal |vauthors=Giordano C, Stassi G, De Maria R, Todaro M, Richiusa P, Papoff G, Ruberti G, Bagnasco M, Testi R, Galluzzo A |title=Potential involvement of Fas and its ligand in the pathogenesis of Hashimoto's thyroiditis |journal=Science |volume=275 |issue=5302 |pages=960–3 |year=1997 |pmid=9020075 |doi= |url=}}</ref><ref name="pmid2196027">{{cite journal |vauthors=de los Santos ET, Keyhani-Rofagha S, Cunningham JJ, Mazzaferri EL |title=Cystic thyroid nodules. The dilemma of malignant lesions |journal=Arch. Intern. Med. |volume=150 |issue=7 |pages=1422–7 |year=1990 |pmid=2196027 |doi= |url=}}</ref><ref name="pmid1987443">{{cite journal |vauthors=Greenspan FS |title=The problem of the nodular goiter |journal=Med. Clin. North Am. |volume=75 |issue=1 |pages=195–209 |year=1991 |pmid=1987443 |doi= |url=}}</ref><ref name="pmid1632470">{{cite journal |vauthors=Isaacson PG, Androulakis-Papachristou A, Diss TC, Pan L, Wright DH |title=Follicular colonization in thyroid lymphoma |journal=Am. J. Pathol. |volume=141 |issue=1 |pages=43–52 |year=1992 |pmid=1632470 |pmc=1886561 |doi= |url=}}</ref><ref name="pmid1726932">{{cite journal |vauthors=Ledent C, Parmentier M, Maenhaut C, Taton M, Pirson I, Lamy F, Roger P, Dumont JE |title=The TSH cyclic AMP cascade in the control of thyroid cell proliferation: the story of a concept |journal=Thyroidology |volume=3 |issue=3 |pages=97–101 |year=1991 |pmid=1726932 |doi= |url=}}</ref><ref name="pmid1371462">{{cite journal |vauthors=Ledent C, Dumont JE, Vassart G, Parmentier M |title=Thyroid expression of an A2 adenosine receptor transgene induces thyroid hyperplasia and hyperthyroidism |journal=EMBO J. |volume=11 |issue=2 |pages=537–42 |year=1992 |pmid=1371462 |pmc=556484 |doi= |url=}}</ref><ref name="pmid7036066">{{cite journal |vauthors=Livolsi VA, Merino MJ |title=Histopathologic differential diagnosis of the thyroid |journal=Pathol Annu |volume=16 |issue=Pt 2 |pages=357–406 |year=1981 |pmid=7036066 |doi= |url=}}</ref><ref name="pmid9274519">{{cite journal |vauthors=Ludgate M, Jasani B |title=Apoptosis in autoimmune and non-autoimmune thyroid disease |journal=J. Pathol. |volume=182 |issue=2 |pages=123–4 |year=1997 |pmid=9274519 |doi=10.1002/(SICI)1096-9896(199706)182:2<123::AID-PATH832>3.0.CO;2-F |url=}}</ref><ref name="pmid3484533">{{cite journal |vauthors=Maceri DR, Sullivan MJ, McClatchney KD |title=Autoimmune thyroiditis: pathophysiology and relationship to thyroid cancer |journal=Laryngoscope |volume=96 |issue=1 |pages=82–6 |year=1986 |pmid=3484533 |doi= |url=}}</ref><ref name="pmid1570743">{{cite journal |vauthors=Moriuchi A, Yokoyama S, Kashima K, Andoh T, Nakayama I, Noguchi S |title=Localized primary amyloid tumor of the thyroid developing in the course of Hashimoto's thyroiditis |journal=Acta Pathol. Jpn. |volume=42 |issue=3 |pages=210–6 |year=1992 |pmid=1570743 |doi= |url=}}</ref><ref name="pmid8242306">{{cite journal |vauthors=McKee RF, Krukowski ZH, Matheson NA |title=Thyroid neoplasia coexistent with chronic lymphocytic thyroiditis |journal=Br J Surg |volume=80 |issue=10 |pages=1303–4 |year=1993 |pmid=8242306 |doi= |url=}}</ref><ref name="pmid3605864">{{cite journal |vauthors=Ott RA, McCall AR, McHenry C, Jarosz H, Armin A, Lawrence AM, Paloyan E |title=The incidence of thyroid carcinoma in Hashimoto's thyroiditis |journal=Am Surg |volume=53 |issue=8 |pages=442–5 |year=1987 |pmid=3605864 |doi= |url=}}</ref><ref name="pmid3285378">{{cite journal |vauthors=Paynter OE, Burin GJ, Jaeger RB, Gregorio CA |title=Goitrogens and thyroid follicular cell neoplasia: evidence for a threshold process |journal=Regul. Toxicol. Pharmacol. |volume=8 |issue=1 |pages=102–19 |year=1988 |pmid=3285378 |doi= |url=}}</ref><ref name="pmid8626858">{{cite journal |vauthors=Berndorfer U, Wilms H, Herzog V |title=Multimerization of thyroglobulin (TG) during extracellular storage: isolation of highly cross-linked TG from human thyroids |journal=J. Clin. Endocrinol. Metab. |volume=81 |issue=5 |pages=1918–26 |year=1996 |pmid=8626858 |doi=10.1210/jcem.81.5.8626858 |url=}}</ref><ref name="pmid1036742">{{cite journal |vauthors=Bialas P, Marks S, Dekker A, Field JB |title=Hashimoto's thyroiditis presenting as a solitary functioning thyroid nodule |journal=J. Clin. Endocrinol. Metab. |volume=43 |issue=6 |pages=1365–9 |year=1976 |pmid=1036742 |doi=10.1210/jcem-43-6-1365 |url=}}</ref>
<ref name="pmid3755697">{{cite journal |vauthors=Aozasa K, Inoue A, Katagiri S, Matsuzuka F, Katayama S, Yonezawa T |title=Plasmacytoma and follicular lymphoma in a case of Hashimoto's thyroiditis |journal=Histopathology |volume=10 |issue=7 |pages=735–40 |year=1986 |pmid=3755697 |doi= |url=}}</ref><ref name="pmid862558">{{cite journal |vauthors=Bastomsky CH |title=Enhanced thyroxine metabolism and high uptake goiters in rats after a single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin |journal=Endocrinology |volume=101 |issue=1 |pages=292–6 |year=1977 |pmid=862558 |doi=10.1210/endo-101-1-292 |url=}}</ref><ref name="pmid8612537">{{cite journal |vauthors=Brix K, Lemansky P, Herzog V |title=Evidence for extracellularly acting cathepsins mediating thyroid hormone liberation in thyroid epithelial cells |journal=Endocrinology |volume=137 |issue=5 |pages=1963–74 |year=1996 |pmid=8612537 |doi=10.1210/endo.137.5.8612537 |url=}}</ref><ref name="pmid8608777">{{cite journal |vauthors=Burch HB |title=Evaluation and management of the solid thyroid nodule |journal=Endocrinol. Metab. Clin. North Am. |volume=24 |issue=4 |pages=663–710 |year=1995 |pmid=8608777 |doi= |url=}}</ref><ref name="pmid2627756">{{cite journal |vauthors=Coclet J, Foureau F, Ketelbant P, Galand P, Dumont JE |title=Cell population kinetics in dog and human adult thyroid |journal=Clin. Endocrinol. (Oxf) |volume=31 |issue=6 |pages=655–65 |year=1989 |pmid=2627756 |doi= |url=}}</ref><ref name="pmid2196027">{{cite journal |vauthors=de los Santos ET, Keyhani-Rofagha S, Cunningham JJ, Mazzaferri EL |title=Cystic thyroid nodules. The dilemma of malignant lesions |journal=Arch. Intern. Med. |volume=150 |issue=7 |pages=1422–7 |year=1990 |pmid=2196027 |doi= |url=}}</ref><ref name="pmid2164546">{{cite journal |vauthors=Di Carlo A, Mariano A, Pisano G, Parmeggiani U, Beguinot L, Macchia V |title=Epidermal growth factor receptor and thyrotropin response in human thyroid tissues |journal=J. Endocrinol. Invest. |volume=13 |issue=4 |pages=293–9 |year=1990 |pmid=2164546 |doi=10.1007/BF03349565 |url=}}</ref><ref name="pmid1661579">{{cite journal |vauthors=Dumont JE, Maenhaut C, Pirson I, Baptist M, Roger PP |title=Growth factors controlling the thyroid gland |journal=Baillieres Clin. Endocrinol. Metab. |volume=5 |issue=4 |pages=727–54 |year=1991 |pmid=1661579 |doi= |url=}}</ref><ref name="pmid7920658">{{cite journal |vauthors=Duprez L, Parma J, Van Sande J, Allgeier A, Leclère J, Schvartz C, Delisle MJ, Decoulx M, Orgiazzi J, Dumont J |title=Germline mutations in the thyrotropin receptor gene cause non-autoimmune autosomal dominant hyperthyroidism |journal=Nat. Genet. |volume=7 |issue=3 |pages=396–401 |year=1994 |pmid=7920658 |doi=10.1038/ng0794-396 |url=}}</ref><ref name="pmid1995765">{{cite journal |vauthors=Ericsson UB, Lindgärde F |title=Effects of cigarette smoking on thyroid function and the prevalence of goitre, thyrotoxicosis and autoimmune thyroiditis |journal=J. Intern. Med. |volume=229 |issue=1 |pages=67–71 |year=1991 |pmid=1995765 |doi= |url=}}</ref><ref name="pmid8026388">{{cite journal |vauthors=Farid NR, Shi Y, Zou M |title=Molecular basis of thyroid cancer |journal=Endocr. Rev. |volume=15 |issue=2 |pages=202–32 |year=1994 |pmid=8026388 |doi=10.1210/edrv-15-2-202 |url=}}</ref><ref name="pmid11172729">{{cite journal |vauthors=Liekens S, De Clercq E, Neyts J |title=Angiogenesis: regulators and clinical applications |journal=Biochem. Pharmacol. |volume=61 |issue=3 |pages=253–70 |year=2001 |pmid=11172729 |doi= |url=}}</ref><ref name="pmid7714083">{{cite journal |vauthors=Gaitan E, Cooksey RC, Legan J, Lindsay RH |title=Antithyroid effects in vivo and in vitro of vitexin: a C-glucosylflavone in millet |journal=J. Clin. Endocrinol. Metab. |volume=80 |issue=4 |pages=1144–7 |year=1995 |pmid=7714083 |doi=10.1210/jcem.80.4.7714083 |url=}}</ref><ref name="pmid1356609">{{cite journal |vauthors=Gaskin D, Parai SK, Parai MR |title=Hashimoto's thyroiditis with medullary carcinoma |journal=Can J Surg |volume=35 |issue=5 |pages=528–30 |year=1992 |pmid=1356609 |doi= |url=}}</ref><ref name="pmid7988459">{{cite journal |vauthors=Gerber H, Huber G, Peter HJ, Kämpf J, Lemarchand-Beraud T, Fragu P, Stocker R |title=Transformation of normal thyroids into colloid goiters in rats and mice by diphenylthiohydantoin |journal=Endocrinology |volume=135 |issue=6 |pages=2688–99 |year=1994 |pmid=7988459 |doi=10.1210/endo.135.6.7988459 |url=}}</ref><ref name="pmid21190442">{{cite journal |vauthors=Wang CC, Friedman L, Kennedy GC, Wang H, Kebebew E, Steward DL, Zeiger MA, Westra WH, Wang Y, Khanafshar E, Fellegara G, Rosai J, Livolsi V, Lanman RB |title=A large multicenter correlation study of thyroid nodule cytopathology and histopathology |journal=Thyroid |volume=21 |issue=3 |pages=243–51 |year=2011 |pmid=21190442 |pmc=3698689 |doi=10.1089/thy.2010.0243 |url=}}</ref><ref name="pmid9429860">{{cite journal |vauthors=Gharib H |title=Changing concepts in the diagnosis and management of thyroid nodules |journal=Endocrinol. Metab. Clin. North Am. |volume=26 |issue=4 |pages=777–800 |year=1997 |pmid=9429860 |doi= |url=}}</ref><ref name="pmid9020075">{{cite journal |vauthors=Giordano C, Stassi G, De Maria R, Todaro M, Richiusa P, Papoff G, Ruberti G, Bagnasco M, Testi R, Galluzzo A |title=Potential involvement of Fas and its ligand in the pathogenesis of Hashimoto's thyroiditis |journal=Science |volume=275 |issue=5302 |pages=960–3 |year=1997 |pmid=9020075 |doi= |url=}}</ref><ref name="pmid2196027">{{cite journal |vauthors=de los Santos ET, Keyhani-Rofagha S, Cunningham JJ, Mazzaferri EL |title=Cystic thyroid nodules. The dilemma of malignant lesions |journal=Arch. Intern. Med. |volume=150 |issue=7 |pages=1422–7 |year=1990 |pmid=2196027 |doi= |url=}}</ref><ref name="pmid1987443">{{cite journal |vauthors=Greenspan FS |title=The problem of the nodular goiter |journal=Med. Clin. North Am. |volume=75 |issue=1 |pages=195–209 |year=1991 |pmid=1987443 |doi= |url=}}</ref><ref name="pmid1632470">{{cite journal |vauthors=Isaacson PG, Androulakis-Papachristou A, Diss TC, Pan L, Wright DH |title=Follicular colonization in thyroid lymphoma |journal=Am. J. Pathol. |volume=141 |issue=1 |pages=43–52 |year=1992 |pmid=1632470 |pmc=1886561 |doi= |url=}}</ref><ref name="pmid1726932">{{cite journal |vauthors=Ledent C, Parmentier M, Maenhaut C, Taton M, Pirson I, Lamy F, Roger P, Dumont JE |title=The TSH cyclic AMP cascade in the control of thyroid cell proliferation: the story of a concept |journal=Thyroidology |volume=3 |issue=3 |pages=97–101 |year=1991 |pmid=1726932 |doi= |url=}}</ref><ref name="pmid1371462">{{cite journal |vauthors=Ledent C, Dumont JE, Vassart G, Parmentier M |title=Thyroid expression of an A2 adenosine receptor transgene induces thyroid hyperplasia and hyperthyroidism |journal=EMBO J. |volume=11 |issue=2 |pages=537–42 |year=1992 |pmid=1371462 |pmc=556484 |doi= |url=}}</ref><ref name="pmid7036066">{{cite journal |vauthors=Livolsi VA, Merino MJ |title=Histopathologic differential diagnosis of the thyroid |journal=Pathol Annu |volume=16 |issue=Pt 2 |pages=357–406 |year=1981 |pmid=7036066 |doi= |url=}}</ref><ref name="pmid9274519">{{cite journal |vauthors=Ludgate M, Jasani B |title=Apoptosis in autoimmune and non-autoimmune thyroid disease |journal=J. Pathol. |volume=182 |issue=2 |pages=123–4 |year=1997 |pmid=9274519 |doi=10.1002/(SICI)1096-9896(199706)182:2<123::AID-PATH832>3.0.CO;2-F |url=}}</ref><ref name="pmid3484533">{{cite journal |vauthors=Maceri DR, Sullivan MJ, McClatchney KD |title=Autoimmune thyroiditis: pathophysiology and relationship to thyroid cancer |journal=Laryngoscope |volume=96 |issue=1 |pages=82–6 |year=1986 |pmid=3484533 |doi= |url=}}</ref><ref name="pmid1570743">{{cite journal |vauthors=Moriuchi A, Yokoyama S, Kashima K, Andoh T, Nakayama I, Noguchi S |title=Localized primary amyloid tumor of the thyroid developing in the course of Hashimoto's thyroiditis |journal=Acta Pathol. Jpn. |volume=42 |issue=3 |pages=210–6 |year=1992 |pmid=1570743 |doi= |url=}}</ref><ref name="pmid8242306">{{cite journal |vauthors=McKee RF, Krukowski ZH, Matheson NA |title=Thyroid neoplasia coexistent with chronic lymphocytic thyroiditis |journal=Br J Surg |volume=80 |issue=10 |pages=1303–4 |year=1993 |pmid=8242306 |doi= |url=}}</ref><ref name="pmid3605864">{{cite journal |vauthors=Ott RA, McCall AR, McHenry C, Jarosz H, Armin A, Lawrence AM, Paloyan E |title=The incidence of thyroid carcinoma in Hashimoto's thyroiditis |journal=Am Surg |volume=53 |issue=8 |pages=442–5 |year=1987 |pmid=3605864 |doi= |url=}}</ref><ref name="pmid3285378">{{cite journal |vauthors=Paynter OE, Burin GJ, Jaeger RB, Gregorio CA |title=Goitrogens and thyroid follicular cell neoplasia: evidence for a threshold process |journal=Regul. Toxicol. Pharmacol. |volume=8 |issue=1 |pages=102–19 |year=1988 |pmid=3285378 |doi= |url=}}</ref><ref name="pmid8626858">{{cite journal |vauthors=Berndorfer U, Wilms H, Herzog V |title=Multimerization of thyroglobulin (TG) during extracellular storage: isolation of highly cross-linked TG from human thyroids |journal=J. Clin. Endocrinol. Metab. |volume=81 |issue=5 |pages=1918–26 |year=1996 |pmid=8626858 |doi=10.1210/jcem.81.5.8626858 |url=}}</ref><ref name="pmid1036742">{{cite journal |vauthors=Bialas P, Marks S, Dekker A, Field JB |title=Hashimoto's thyroiditis presenting as a solitary functioning thyroid nodule |journal=J. Clin. Endocrinol. Metab. |volume=43 |issue=6 |pages=1365–9 |year=1976 |pmid=1036742 |doi=10.1210/jcem-43-6-1365 |url=}}</ref>
* Thyroid nodules may arise from different [[Cell (biology)|cells]] in [[thyroid]] parenchyma. The [[pathogenesis]] of developing a thyroid nodule may differ based on the type of the [[nodule]], and whether it is [[malignant]] or [[benign]].
* Basically thyroid nodules may develop secondary to [[hyperplasia]], [[mutations]] and resultant [[carcinoma]], excess [[colloid]] accumulation, or from[[inflammation]] of [[Thyroid gland|thyroid tissue]].


=== Hyperplastic nodules ===
=== (a) Hyperplastic nodules ===
[[Hyperplasia|Hyperplastic]] nodule pathogenesis seems to start with an increase in thyroid [[proliferation]], which lead to thyroid [[hyperplasia]]. Rapid thyroid prolifertion mainly occur in response to certain stimulants. Stimulants mainly act through [[TSH]] mediated activity and production. Following the [[hyperplasia]] development phase, a new phase may begin, leading to a [[neoplasia]].
* [[Hyperplasia|Hyperplastic]] nodule [[pathogenesis]] seems to start with an increase in [[Thyroid Gland|thyroid]] [[proliferation]], which lead to [[Thyroid Gland|thyroid]] [[hyperplasia]].  
* Rapid [[Proliferation|thyroid proliferation]] mainly occur in response to certain stimulants.
* Stimulants mainly act through [[TSH]] mediated activity and production. Following the [[hyperplasia]] development phase, a new phase may begin, leading to a [[neoplasia]].


==== TSH role in thyroid nodule formation ====
==== 1. TSH role in thyroid nodule formation ====
Growth signals in thyroid tissue start their pathways by an stimulant, that attaches to the thyroid receptors. The following signals can be transmitted through 3 distinct pathways:
* Growth signals in [[Thyroid Gland|thyroid tissue]] start by a stimulant, that attaches to the [[Thyroid Gland|thyroid]] receptors. The following signals can be transmitted through 3 distinct pathways:
* [[Adenylate cyclase]]/[[Protein kinase A|protein kinase A system]]
** [[Adenylate cyclase]]/[[Protein kinase A|protein kinase A system]]
* [[Phospholipase C|Phospholipase C pathways]]
** [[Phospholipase C|Phospholipase C pathways]]
* [[Phospholipase A2|Phospholipase A2 system]] (intracellular metabolism of [[prostaglandins]])
** [[Phospholipase A2|Phospholipase A2 system]] ([[intracellular]] metabolism of [[prostaglandins]])
The most important and effective pathway for thyroid growth is the activation of [[adenylate cyclase]]/[[Protein kinase A|protein kinase A system]]. Activation of [[Phospholipase c|phospholipase C]] and [[phospholipase A2]] have only a minor or absent effect on thyroid growth. 


[[TSH]] acts as an stimulant by binding to the receptor and activating both the [[adenylate cyclase]] and [[phospholipase C]] pathways. As mentioned, the [[phospholipase C]] pathways has minor effects, and most of the [[TSH]] effect on cell growth is generated by [[adenylate cyclase]] pathway. The signal generated by the [[adenylate cyclase]] [[CAMP-dependent protein kinase|cAMP-dependent]] pathways is then transduced into the [[nucleus]] where [[transcription factors]]–upon [[phosphorylation]]–induce the expression of cAMP-inducible genes. It has been definitely established that [[TSH]] has a main [[mitogenic]] role, through [[cAMP]], Gs [[proteins]] and [[Protein kinase A|protein kinase A,]] which activates the metabolic cascade leading to the stimulation of growth.  
* The most important pathway for [[Thyroid Gland|thyroid]] growth is the activation of [[adenylate cyclase]]/[[Protein kinase A|protein kinase A system]]. Activation of [[Phospholipase c|phospholipase C]] and [[phospholipase A2]] have only a minor effect on [[Thyroid Gland|thyroid]] growth. 
* [[TSH]] acts as a stimulant by binding to the [[Thyrotropin receptor|TSH receptor]] and leads to activation of both the [[adenylate cyclase]] and [[phospholipase C]] pathways. As mentioned, the [[phospholipase C]] pathway has minor effects, and most of the [[TSH]] effect on [[Cell (biology)|cell]] growth is generated by [[adenylate cyclase]] pathway. The signal generated by the [[adenylate cyclase]] [[CAMP-dependent protein kinase|cAMP-dependent]] pathway is then [[Transduction|transduced]] in the [[nucleus]] where [[transcription factors]]–upon [[phosphorylation]]–induce the expression of [[Cyclic adenosine monophosphate|cAMP]]-inducible [[genes]]. It has been established that [[TSH]] has a main [[mitogenic]] role, through [[cAMP]], Gs [[proteins]] and [[Protein kinase A|protein kinase A,]] which activates the metabolic cascade leading to the stimulation of growth.
* However, to produce [[hyperplasia]], overproduction of [[cAMP]] must be continuous, as it occurs in [[mutations]] constitutive of the [[genes]] which regulate [[cAMP]] production. 
* Constitutive [[Cyclic adenosine monophosphate|cAMP]] overproduction has been demonstrated to be due to [[Point mutations|point mutation]] of the [[Thyrotropin receptor|TSH receptor]] or [[G proteins|Gs protein]]. 
* Constitutive [[Cyclic adenosine monophosphate|cAMP]] overproduction not only stimulates growth but also function. 
* [[Hyperplastic]] thyroid nodule [[pathogenesis]] can be divided into 2 phases: 


However, to produce [[hyperplasia]], overproduction of [[cAMP]] must be continuous, as it occurs in mutations constitutive of the genes which regulate cAMP production. Constitutive cAMP overproduction has been demonstrated to be due to point mutation of the TSH receptor or Gs protein
==== 2. Thyroid overgrowth stimulants: ====
 
[[Thyroid Gland|Thyroid]] normally has a low [[Proliferation|proliferative]] activity, although it can start [[proliferation]] rapidly in response to certain stimulants. Stimulants mainly act through [[Thyroid-stimulating hormone|TSH]] mediated activity and production. The following stimulants appear to have the most important role in [[pathogenesis]] of [[hyperplastic]] nodules:<ref name="pmid2921306">{{cite journal |vauthors=Gaitan E, Lindsay RH, Reichert RD, Ingbar SH, Cooksey RC, Legan J, Meydrech EF, Hill J, Kubota K |title=Antithyroid and goitrogenic effects of millet: role of C-glycosylflavones |journal=J. Clin. Endocrinol. Metab. |volume=68 |issue=4 |pages=707–14 |year=1989 |pmid=2921306 |doi=10.1210/jcem-68-4-707 |url=}}</ref><ref name="pmid1696490">{{cite journal |vauthors=Gaitan E |title=Goitrogens in food and water |journal=Annu. Rev. Nutr. |volume=10 |issue= |pages=21–39 |year=1990 |pmid=1696490 |doi=10.1146/annurev.nu.10.070190.000321 |url=}}</ref>
Constitutive cAMP overproduction not only stimulates growth but also function.
* [[Iodine]] deficiency:
 
Hyperplastic thyroid nodule pathogenesis can be devided into 2 phases:
 
==== 1. Thyroid overgrowth stimulants: ====
Thyroid normally has a low proliferative activity, although it can start proliferation rapidly in response to certain stimulants. Stimulants mainly act through TSH mediated activity and production. The following stimulants look like to have the most important role in pathogenesis of hyperplastic nodules:<ref name="pmid2921306">{{cite journal |vauthors=Gaitan E, Lindsay RH, Reichert RD, Ingbar SH, Cooksey RC, Legan J, Meydrech EF, Hill J, Kubota K |title=Antithyroid and goitrogenic effects of millet: role of C-glycosylflavones |journal=J. Clin. Endocrinol. Metab. |volume=68 |issue=4 |pages=707–14 |year=1989 |pmid=2921306 |doi=10.1210/jcem-68-4-707 |url=}}</ref><ref name="pmid1696490">{{cite journal |vauthors=Gaitan E |title=Goitrogens in food and water |journal=Annu. Rev. Nutr. |volume=10 |issue= |pages=21–39 |year=1990 |pmid=1696490 |doi=10.1146/annurev.nu.10.070190.000321 |url=}}</ref>
* Iodine deficiency:
** Effects directly or indirectly 
** Effects directly or indirectly 
** The most important potent stimulator of the replicative potential of the gland 
** The most potent stimulator replication of the [[Cell (biology)|cells]] of [[thyroid gland]] 
** Mechanism of action:
** Mechanism of action:
*** Acting as an initiator for TSH rise
*** Acts as an initiator for TSH rise
*** May enhance the effect of other chemicals that induce a rise in TSH by inducing the promotor overactivity  
*** May enhance the effect of other chemicals that induce a rise in [[TSH]] by inducing the promotor overactivity  
*** The most important reason of high prevalence of thyroid hyperplasia and nodules in iodine-deficient areas
*** The most important reason of high [[prevalence]] of [[Thyroid Gland|thyroid]] hyperplasia and nodules in [[iodine]]-deficient areas
* Industrial chemicals:
* Industrial chemicals:
** DDT
** [[DDT]]
** Polychlorinated byphenyls
** [[Polychlorinated biphenyl|Polychlorinated biphenyls]]
** Pesticides
** [[Pesticides]]
* Goitrogens:
* Goitrogens:
** Complex anions and inorganic atoms (iodine, lithium, CLO4–, TcO4–, BF4–)  
** Complex [[anions]] and inorganic [[atoms]] ([[iodine]], [[lithium]], CLO4–, TcO4–, BF4–)  
** Thiocyanate (SCN–)  
** [[Thiocyanate]] (SCN–)  
** Goitrin, isolated in plants of the genus ''brassica''
** Goitrin, isolated in plants of the [[genus]] Brassica
** Aniline derivatives (sulfonamides, tolbutamide, sulfaguanidine, sulfamethoxazole, etc.)
** [[Aniline]] derivatives ([[sulfonamides]], [[tolbutamide]], [[sulfaguanidine]], [[sulfamethoxazole]], etc.)
** Phenol derivatives and polyhydroxyphenols
** [[Phenol]] derivatives and polyhydroxyphenols
** Flavonoids:
** [[Flavonoids]]:
*** TPO inhibitors
*** [[Thyroid peroxidase|TPO]] inhibitors
*** Also act on thyroid metabolism by interacting with the nuclear receptor for thyroid hormones
*** Also act on [[Thyroid Gland|thyroid]] metabolism by interacting with the [[nuclear]] [[receptor]] for [[thyroid hormones]]
* Antithyroid drugs:
* [[Antithyroid]] drugs:
** Thionamides that are used in the treatment of hyperthyroidism
** Thionamides that are used in the treatment of [[hyperthyroidism]]
* Tobacco:
* [[Tobacco]]:
** May be the reason of high prevalence of thyroid hyperplasia and nodules in iodine-sufficient areas 
** May be the reason of high [[prevalence]] of [[Thyroid Gland|thyroid]] [[hyperplasia]] and nodules in [[iodine]]-sufficient areas 
Thyroid stromal cells interact with thyroid follicular cells by cytokines. Inappropriate cytokine activities also seem to be related to TSH overproduction and thyroid hyperplastic nodule formation. The most important cytokines that can exert an action of differentiation or inhibition of thyroid growth are:
* TGFβ
* IFNγ
* IL-6
* Somatostatin


===== 2. Hyperplasia development phase: =====
* [[Thyroid]] [[stromal cells]] interact with [[thyroid]] follicular [[Cells (biology)|cells]] by cytokines. Inappropriate [[cytokine]] activities also seem to be related to [[TSH]] overproduction and [[thyroid]] hyperplastic nodule formation. The most important [[cytokines]] that may lead to differentiation or inhibition of [[Thyroid Gland|thyroid]] growth are:
Thyroid cells produce the angiogenic vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) sensitive to TSH stimulation. The vascular growth factor induces neovascularization by binding to specific receptors on endothelial cells and stimulating new vessel production. In response, endothelial cells produce growth factors that increase thyropid proliferaion and lead to thyroid hyperplasia. Neovascularization in thyroid matrix is accompanied by the production of proteolytic enzymes, which facilitate the expansion of thyroid tissue into the extracellular matrix.
** [[TGF beta|TGFβ]]
** [[Interferon|IFNγ]]
** [[Interleukin 6|IL-6]]
** [[Somatostatin]]


===== Neoplasia development phase: =====
===== 3. Hyperplasia development phase: =====
each follicle is composed of different clones of cells (polyclonal) but during nodule formation they replicate in a simultaneous and coordinated manner, so each follicle of the nodule reproduces the same heterogeneity of the mother follicle. When a neoplasm arises in the nodule, then the neoplastic follicle shows a monoclonal pattern, suggesting that cancer arises from a single cell. 
* [[Thyroid Gland|Thyroid]] [[Cells (biology)|cells]] produce the [[angiogenic]] [[vascular endothelial growth factor]]/[[vascular]] permeability factor ([[VEGF]]/VPF) sensitive to [[TSH]] stimulation.
* The [[vascular]] growth factor induces [[neovascularization]] by binding to specific receptors on [[endothelial cells]] and stimulating new [[Blood vessel|vessel]] production.
* In response, [[endothelial cells]] produce [[growth factors]] that increase [[thyroid]] [[cell]] [[proliferation]] and lead to [[Thyroid Gland|thyroid]] [[hyperplasia]].  
* [[Neovascularization]] in [[Thyroid Gland|thyroid]] matrix is accompanied by the production of [[Proteolytic enzyme|proteolytic enzymes]], which facilitate the expansion of [[Thyroid Gland|thyroid]] tissue into the [[extracellular matrix]].


activated oncogenes are considered the underlying event leading to uncontrolled cell growth.  
===== 4. Neoplasia development phase: =====
* Each follicle is composed of different clones of [[Cell (biology)|cells]] ([[polyclonal]]), but during nodule formation they replicate in a simultaneous and coordinated manner, so each follicle of the nodule reproduces the same heterogeneity of the mother follicle.
* When a [[neoplasm]] arises in the nodule, then the [[Neoplastic disease|neoplastic]] follicle shows a [[monoclonal]] pattern, suggesting that [[cancer]] arises from a single [[cell]]. 


=== Neoplastoc nodules ===
* Activation of [[oncogenes]] is considered the underlying event leading to uncontrolled [[cell]] growth.  
Neoplastic nodules development mainly involve the activation of proto-oncogenes as the underlying event leading to uncontrolled cell growth. Proto-oncogens activation are associated with thyroid adenoma, hyperplasia, and malignancies. Thyroid gland is made of different follicles, and each follicle is composed of different clones of cells (polyclonal). During nodule formation, cells replicate in a coordinated way simultanously, so each follicle of the nodule share the same heterogenity with other cells. Hyperplastic thyroid nodules are considered as risk factor for neoplasia development, as these cells may express neoplasia during their rapid proliferation phase. During neoplasm formation in the nodule, the neoplastic follicle mostly shows a monoclonal pattern. These findings may indicate that neoplasia arises from a single cell genetic mutation.  The most important oncogens related to thyroid neoplasia development are mentioned in the genetic table below.<ref name="pmid19209125">{{cite journal |vauthors=Taccaliti A, Boscaro M |title=Genetic mutations in thyroid carcinoma |journal=Minerva Endocrinol. |volume=34 |issue=1 |pages=11–28 |year=2009 |pmid=19209125 |doi= |url=}}</ref><ref name="pmid10834397">{{cite journal |vauthors=Vecchio G, Santoro M |title=Oncogenes and thyroid cancer |journal=Clin. Chem. Lab. Med. |volume=38 |issue=2 |pages=113–6 |year=2000 |pmid=10834397 |doi=10.1515/CCLM.2000.017 |url=}}</ref><ref name="pmid7629379">{{cite journal |vauthors=Fusco A, Santoro M, Grieco M, Carlomagno F, Dathan N, Fabien N, Berlingieri MT, Li Z, De Franciscis V, Salvatore D |title=RET/PTC activation in human thyroid carcinomas |journal=J. Endocrinol. Invest. |volume=18 |issue=2 |pages=127–9 |year=1995 |pmid=7629379 |doi=10.1007/BF03349720 |url=}}</ref><ref name="pmid8806699">{{cite journal |vauthors=Fugazzola L, Pierotti MA, Vigano E, Pacini F, Vorontsova TV, Bongarzone I |title=Molecular and biochemical analysis of RET/PTC4, a novel oncogenic rearrangement between RET and ELE1 genes, in a post-Chernobyl papillary thyroid cancer |journal=Oncogene |volume=13 |issue=5 |pages=1093–7 |year=1996 |pmid=8806699 |doi= |url=}}</ref><ref name="pmid8918855">{{cite journal |vauthors=Eng C, Clayton D, Schuffenecker I, Lenoir G, Cote G, Gagel RF, van Amstel HK, Lips CJ, Nishisho I, Takai SI, Marsh DJ, Robinson BG, Frank-Raue K, Raue F, Xue F, Noll WW, Romei C, Pacini F, Fink M, Niederle B, Zedenius J, Nordenskjöld M, Komminoth P, Hendy GN, Mulligan LM |title=The relationship between specific RET proto-oncogene mutations and disease phenotype in multiple endocrine neoplasia type 2. International RET mutation consortium analysis |journal=JAMA |volume=276 |issue=19 |pages=1575–9 |year=1996 |pmid=8918855 |doi= |url=}}</ref><ref name="pmid1468509">{{cite journal |vauthors=Goretzki PE, Simon D, Röher HD |title=G-protein mutations in thyroid tumors |journal=Exp. Clin. Endocrinol. |volume=100 |issue=1-2 |pages=14–6 |year=1992 |pmid=1468509 |doi=10.1055/s-0029-1211167 |url=}}</ref>


Environmental factors can play an important role in triggering the oncogen mutation. The most important carcinogens involved in the pathogenesis of neoplastic thyroid nodules are:
=== (b) Neoplastic nodules ===
* Thionamid compounds: thiourea, methimazole, ethylenethiourea (ETU), thiouracil, propylthiouracil
* [[Neoplastic disease|Neoplastic]] nodules development mainly involve the activation of [[Proto oncogenes|proto-oncogenes]] as the underlying event leading to uncontrolled cell growth.
* Aminotriazole: herbicide
* [[Proto-oncogene]] activation is associated with [[thyroid adenoma]], [[hyperplasia]], and [[malignancies]].
* Acetylaminofluorene (AAF). Use: insecticide
* [[Thyroid gland]] is made up of different follicles, and each follicle is composed of different clones of [[Cells (biology)|cells]] ([[polyclonal]]). During nodule formation, cells replicate in a coordinated fashion simultanously, so each follicle of the nodule shares the same heterogenity with other [[Cell (biology)|cells]].
* Oxydianiline (ODA). Use: Azo-Dye
* [[Hyperplasia|Hyperplastic]] thyroid nodules are considered a [[risk factor]] for the development of [[neoplasia]], as these cells may express [[neoplastic]] potential during their rapid [[proliferation]] phase.
* Methylene benzenamine. Use: Dye intermediate
* During [[neoplasm]] formation in the nodule, the [[neoplastic]] follicle mostly shows a [[monoclonal]] pattern. These findings may indicate that [[neoplasia]] arises from a single [[cell]] [[genetic mutation]].  The most important [[oncogenes]] related to thyroid neoplasia development are mentioned in the genetic table below.<ref name="pmid19209125">{{cite journal |vauthors=Taccaliti A, Boscaro M |title=Genetic mutations in thyroid carcinoma |journal=Minerva Endocrinol. |volume=34 |issue=1 |pages=11–28 |year=2009 |pmid=19209125 |doi= |url=}}</ref><ref name="pmid10834397">{{cite journal |vauthors=Vecchio G, Santoro M |title=Oncogenes and thyroid cancer |journal=Clin. Chem. Lab. Med. |volume=38 |issue=2 |pages=113–6 |year=2000 |pmid=10834397 |doi=10.1515/CCLM.2000.017 |url=}}</ref><ref name="pmid7629379">{{cite journal |vauthors=Fusco A, Santoro M, Grieco M, Carlomagno F, Dathan N, Fabien N, Berlingieri MT, Li Z, De Franciscis V, Salvatore D |title=RET/PTC activation in human thyroid carcinomas |journal=J. Endocrinol. Invest. |volume=18 |issue=2 |pages=127–9 |year=1995 |pmid=7629379 |doi=10.1007/BF03349720 |url=}}</ref><ref name="pmid8806699">{{cite journal |vauthors=Fugazzola L, Pierotti MA, Vigano E, Pacini F, Vorontsova TV, Bongarzone I |title=Molecular and biochemical analysis of RET/PTC4, a novel oncogenic rearrangement between RET and ELE1 genes, in a post-Chernobyl papillary thyroid cancer |journal=Oncogene |volume=13 |issue=5 |pages=1093–7 |year=1996 |pmid=8806699 |doi= |url=}}</ref><ref name="pmid8918855">{{cite journal |vauthors=Eng C, Clayton D, Schuffenecker I, Lenoir G, Cote G, Gagel RF, van Amstel HK, Lips CJ, Nishisho I, Takai SI, Marsh DJ, Robinson BG, Frank-Raue K, Raue F, Xue F, Noll WW, Romei C, Pacini F, Fink M, Niederle B, Zedenius J, Nordenskjöld M, Komminoth P, Hendy GN, Mulligan LM |title=The relationship between specific RET proto-oncogene mutations and disease phenotype in multiple endocrine neoplasia type 2. International RET mutation consortium analysis |journal=JAMA |volume=276 |issue=19 |pages=1575–9 |year=1996 |pmid=8918855 |doi= |url=}}</ref><ref name="pmid1468509">{{cite journal |vauthors=Goretzki PE, Simon D, Röher HD |title=G-protein mutations in thyroid tumors |journal=Exp. Clin. Endocrinol. |volume=100 |issue=1-2 |pages=14–6 |year=1992 |pmid=1468509 |doi=10.1055/s-0029-1211167 |url=}}</ref>
* Nitrosamines
 
* Nitrosoureas (NMU), (NBU), (ENU). Use: derivatives (BCNU, CCNU, MeCCNU) are drugs against tumors. Streptozocin (naturally occurring nitrosourea) is used in the treatment of islet-cell carcinoma of the pancreas)
* Environmental factors can play an important role in triggering the [[oncogene]] [[mutation]]. The most important carcinogens involved in the [[pathogenesis]] of [[neoplastic]] thyroid nodules are:
** [[Thioamide]] compounds
*** [[Thiourea]]
*** [[Methimazole]]
*** Ethylenethiourea (ETU)
*** [[Thiouracil]]
*** [[Propylthiouracil]]
** Aminotriazole: [[Herbicide]]
** Acetylaminofluorene (AAF)
** Use: [[Insecticide]]
** Oxydianiline (ODA)
** Use: Azo-Dye
** [[Methylene]] [[Benzenamine, 3-(trifluoromethyl)-|benzenamine]]
** Use: Dye intermediate
** [[Nitrosamine|Nitrosamines]]
** [[Nitrosourea|Nitrosoureas]] (NMU), (NBU), (ENU)
** Use: derivatives (BCNU, CCNU, MeCCNU) are drugs against [[Tumor|tumors]]
** [[Streptozocin]] (naturally occurring [[nitrosourea]]) is used in the treatment of islet-cell [[carcinoma]] of the [[pancreas]]


==== Papillary thyroid carcinoma ====
==== Papillary thyroid carcinoma ====
Schematic representation of the MAPK signaling cascade in papillary thyroid carcinoma. MAPK, also known as ERK, translocates to the nucleus and promotes cell division when it is phosphorylated by MEK, a serine/threonine kinase. Constitutive activation of this process is tumorigenic. MAPK phosphorylation is a relatively distal step in a sequential phosphorylation cascade that can begin with the activation of a tyrosine kinase, is followed by phosphorylation of RAS which activates BRAF, a serine/threonine kinase followed by MEK and MAPK phosphorylation. In papillary thyroid carcinoma, somatic genetic alterations at three of these steps activate this linear signaling cascade. A gene rearrangement creating a chimeric RET or TRK activates the initial tyrosine kinase step. Activating point mutations of either RAS or BRAF constitutively activates these proteins. The tyrosine kinase, RAS, and BRAF genetic alterations are usually mutually exclusive, suggesting that any single alteration is sufficient to play an early role in tumorigenesis [1,2].
* The most important [[pathogenic]] factor involved in developing [[papillary thyroid cancer]] is an [[intracellular]] signaling pathway called [[Mitogen-activated protein kinase|MAPK]] pathyway ([[Mitogen-activated protein kinase|Mitogen-activated protein kinases]]), also known as ERK pathway ([[Extracellular signal-regulated kinases|extracellular signal-regulated kinase]]). After [[antigen]] binding to [[tyrosine]] receptors, [[Mitogen-activated protein kinase|MAPK]] is translocated into the [[Cell nucleus|nucleus]]. Receptor activation leads to [[cell division]], after [[phosphorylation]] by MEK (a [[serine]]/[[threonine]] [[kinase]]).  
* Other steps leading to [[Mitogen-activated protein kinase|MAPK]] [[phosphorylation]] include [[phosphorylation]] of [[RAS]] which activates [[BRAF]], a [[serine]]/[[threonine]] [[kinase]] followed by MEK and [[Mitogen-activated protein kinase|MAPK]] [[phosphorylation]].  
* In [[Papillary thyroid cancer|papillary thyroid carcinoma]], a [[somatic mutation]] may lead to activation of this linear signaling cascade.
* As a result, there will be increased [[Transcription (genetics)|transcription]] of [[nuclear]] [[proteins]], which lead to un-regulated activity and reproduction of [[cancerous]] [[Cells (biology)|cells]]. This implies that any single alteration is sufficient to play an early role in tumorigenesis.<ref name="pmid11390647">{{cite journal |vauthors=Melillo RM, Santoro M, Ong SH, Billaud M, Fusco A, Hadari YR, Schlessinger J, Lax I |title=Docking protein FRS2 links the protein tyrosine kinase RET and its oncogenic forms with the mitogen-activated protein kinase signaling cascade |journal=Mol. Cell. Biol. |volume=21 |issue=13 |pages=4177–87 |year=2001 |pmid=11390647 |pmc=87079 |doi=10.1128/MCB.21.13.4177-4187.2001 |url=}}</ref><ref name="pmid16946010">{{cite journal |vauthors=Ciampi R, Nikiforov YE |title=RET/PTC rearrangements and BRAF mutations in thyroid tumorigenesis |journal=Endocrinology |volume=148 |issue=3 |pages=936–41 |year=2007 |pmid=16946010 |doi=10.1210/en.2006-0921 |url=}}</ref>
'''Abbrevaitions:'''


ERK: extracellular signal-regulated kinase; MAPK: mitogen-activated protein kinase.
'''ERK:''' [[extracellular signal-regulated kinase]]; '''MAPK:''' [[mitogen-activated protein kinase]]


thyrosin kinase    RAS    BRAF  MEK  MAPK    nucleus    tumorogenesis
=== (c) Colloid and cystic nodules ===
# Melillo RM, Castillone D, Guarino V, et al. The ret/ptc-ras-braf linear signaling cascade mediates the motile and mitogenic phenotype of thyroid cancer cells. J Clin Invest 2005; 115:1068.
# Ciampi R, Nikiforov YE. Ret/ptc rearrangements and braf mutations in thyroid tumorigenesis. Endocrinology 2007; 148:936.


=== Colloid and cystic nodules ===
==== 1. Colloid nodules   ====
* The colloid nodules consist of colloid droplets and [[thyroglobulin]] vesicles.
* [[Thyroid gland]] keeps a balance between colloid and [[thyroglobulin]] production by regulating the secretion of [[thyroglobulin]] into colloid and reabsorption of colloid into thyroid follicular cells. This regulation is maintained by macro-[[pinocytosis]] ([[Pseudopod|pseudopods]]) and micro-[[pinocytosis]] ([[microvilli]]).
* Any imbalance between secretion and reabsorption of [[thyroglobulin]] leads to a disruption of the equilibrium, and produces a colloid appeared thyroid nodule. These nodules may also be produced as a defect of intraluminal thyroglobulin reabsorption. 


==== Colloid nodules ====
==== 2. Iodine related nodules pathogenesis: ====
The colloid nodules consist of colloid droplets and thyroglobulin vesicles. Thyroid gland keeps a balance between colloid and thyroglobulin production by interacting between secretion of thyroglobulin into colloid and reabsorption of colloid into thyroid follicular cells. The mentioned interaction is processed by macro-pinocytosis (pseudopods) and micro-pinocytosis (microvilli). Any imbalance between secretion and reabsorption of thyroglobulin equilibrium produces a colloid appeared thyroid nodule. These nodules may also be produced as a defect of intraluminal thyroglobulin reabsorption. 
[[Iodine]] excess can lead to colloid nodules in [[thyroid gland]], leading to a colloid [[goitre]]:
* [[Endocytosis]] inhibition: High dosage of [[iodine]] may lead to inhibition of the [[protease]] activity of [[Thyroid Gland|thyroid]] [[Lysosome|lysosomes]] thereby inhibiting [[endocytosis]]
* [[Exocytosis]] inhibition: [[Iodine]] reduces the expression of the [[TSH receptor]] on the surface of [[Thyroid Gland|thyroid]] cells thereby inhibiting and decreasing colloid reabsorption
* [[Iodine]] excess in combination with [[Thyroid-stimulating hormone|TSH]] over activity may lead to colloid goitre
Another mechanism that may lead to colloid goitre formation is loss of [[thyroglobulin]] packaging ability, that may lead to an enormous enlargement of the follicles and flattening of the [[epithelium]].  


==== Iodine related nodules pthogenesis: ====
==== 3. Cystic thyroid nodules ====
Iodine excess can lead to colloid nodules in thyroid gland, leading to a colloid goitre. The mechanism is due to several idoine effects on thyroid cells:
Cystic thyroid nodules may be classified into the following types:
* Endocytosis inhibition: High dosage of iodine may lead to inhibition of the protease activity of thyroid lysosomes, and thereby inhibiting endocytosis
* [[Necrosis|Necrotic]] cystic nodules:
* Exocytosis inhibition: Iodine reduces the expression of the TSH receptor on the surface of thyroid cells, and thereby inhibiting and decreasing colloid reabsorption
** May be due to a relative deficiency of [[blood]] supply:
* Iodine excess in combination with TSH over activity may lead to colloid goitre
*** Inadequate [[blood]] supply for [[neoplastic]] growth
Another mechanism that may lead to colloid goitre formation is due to loss of thyroglobulin packaging ability, that may lead to an enormous enlargement of the follicles and flattening of the epithelium. Therefore a colloid nodular goitre can be made.
*** Imbalance between [[angiogenesis]] and [[Cell (biology)|cell]] growth
*** Compression of new [[Blood vessel|vessels]] due to mass effect, leading to [[Cell (biology)|cell]] damage and [[necrosis]]
** [[Hyperplasia|Hyperplastic]] thyroid nodules may proceed towards [[necrosis]], colliquation, and [[pseudocyst]] formation
* [[Serum]]-like cystic nodules:
** May be related to [[autoimmunity]]
* [[Apoptotic]] cystic nodules:
** Cysts that may be related to normal [[cellular]] [[apoptosis]] or [[neoplastic]]/infected [[cellular]] [[apoptosis]]
* [[Vascular]] growth factor related cystic nodules:
** Cyst formation may be the result of an increased concentration of [[Vascular endothelial growth factor|VEGF]]/VPF inside the cystic area
** [[VEGF]]/VPF lead to stimulation of [[vascular permeability]] and promoting the accumulation of [[fluids]] in the cysts
** [[Vascular endothelial growth factor|VEGF]]/VPF are particularly found in the cystic fluid of rapidly enlarging or recurrent cysts


==== Cystic thyroid nodules ====
=== (d) Thyroiditic nodule ===
Cystic thyroid nodules can be classified into the following types:
Nodular [[lymphocytic thyroiditis]] almost always present in combination with other thyroiditic diseases. They can also present as a part of [[infection]]. It has been shown that the ability of [[super-antigens]] (SAgs) to activate the [[immune system]] may play a role in the course of [[autoimmune disorders]]. In most of these cases, the mechanism of nodular lesion is the same as the mechanism of the main disease, implying that the thyroid nodule is a part of normal disease pattern. Many of these nodules are not identifiable based on [[Physical examination|physical exam]], and are detected during [[thyroid]] [[scintigraphy]]. The most important thyroiditic diseases that may present as [[lymphocytic]] nodular [[thyroid]] are:
* Necrotic cystic nodules:
* Local [[infections]]:
** May be due to a relative insufficiency of blood supply
** [[Pyogenic infection]]
*** Inadequate blood supply for a neoplastic cells growth
**[[Tuberculosis]]
*** Imbalance between angiogenesis and cell growth
**[[Parasites]]
*** Compression of new vessels due to lack of cellular outgrow, leading to cell damage, necrosis and colliquation
* [[De Quervain's thyroiditis|Subacute de Quervain’s]] thyroiditis
** Hyperplastic thyroid nodules may proceed towards necrosis, colliquation, and pseudocyst formation
* [[Riedel's thyroiditis|Fibrosing (Riedel’s) thyroiditis]]
* Serum-like cystic nodules:
* [[Plasma cell]] [[granuloma]]
** May be related to autoimmunity
* [[Plasmacytoma]]
* Apoptotic cystic nodules:
* Primary [[amyloid]] [[tumor]] and [[amyloidosis]]
** Cysts that may be related to normal cellular apoptosis or neoplastic/infected cellular apoptosis
* [[Thymoma]]
* Vascular growth factor related cystic nodules:
* [[Primary thyroid lymphoma]]
** Cyst formation may be the result of an increased concentration of VEGF/VPF inside the cystic area
** Thyroiditic nodule due to [[Diffuse large B cell lymphoma|diffuse B-cell]] infiltration into [[lymphoma]] presented areas
** VEGF/VPF lead to stimulation of vascular permeability and promoting the accumulation of fluids in the cysts
* [[Histiocytosis X]]
** VEGF/VPF are particularly found in the cystic fluid of rapidly enlarging or recurrent cysts
* [[Medullary carcinoma of the thyroid|Medullary carcinoma]]
 
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
=== Thyroiditic nodule ===
** Thyroiditic nodule may be due to an [[immune response]] to some abnormal [[Thyroid Gland|thyroid]] antigen expressed in the [[tumor]]
Nodular lymphocytic thyroiditis almost always present in combination with other thyroiditic diseases. They can also present as a part of infection. It has been shown that the ability of super antigens (SAgs) to activate the immune system may play a role in the course of autoimmune disorders. In most of these thyroiditis diseases, the mechanism of nodular lesion is the same as the mechanism of the main disease, meaning that the thyroid nodule is a part of normal disease pattern. Many of these nodules are not identifiable based on physical exam, and are detected during thryoid scintigraphy. The most important thyroiditic diseases that may present as lymphocytic nodular thyroid are:
* Local infections:
** Piogenic infection
**Tuberculosis
**Parasites
* Subacute de Quervain’s thyroiditis
* Fibrosing (Riedel’s) thyroiditis
* Plasmacell granuloma
* Plasmacytoma
* Primary amyloid tumor and amyloidosis
* Thymoma
* Primary thyroid lymphoma
** Thyroiditic nodule due to diffuse B-cell infiltration into lymphoma presented areas
* Histocytosis X
* Medullary carcinoma
* Papillary carcinoma
** Thyroiditic nodule may be due to an immune response to some abnormal thyroid antigen expressed in the tumor


==Genetics==
==Genetics==
Genetic mutation is considered as one of the most important mechanisms of developing thyroid nodules, especially neoplastic thyroid nodules. Most of these mutations occur as somatic mutations, while some may occur in a familial order. The most important category of familial thyroid cancers are due to genetic mutations, and are called familial nonmedullary thyroid cancer FNMTC, with the following features:
[[Genetic mutation]] is considered as one of the most important mechanisms of developing thyroid nodules, especially [[Thyroid Cancer|neoplastic thyroid nodules]]. Most of these [[mutations]] occur as [[Somatic mutation|somatic mutations]], while some may occur in a familial order. The most important category of familial [[thyroid cancers]] are due to [[genetic mutations]], and are called familial non-[[medullary thyroid cancer]] (FNMTC), with the following features:
* A rare group ofcancers
* Rare group of [[Cancer|cancers]]
* Mostly related to non-medullary tumors
* Related to other non-medullary [[tumors]]
* Inheritance: autosomal dominant with incomplete penetrance and variable expressivity
* Inheritance: [[Autosomal dominant]] with [[incomplete penetrance]] and variable expressivity
* Affected patients have a earlier age of thyroid cancer onset
* Affected patients in an earlier age
* Associated with:
* Associated with:
** More benign thyroid nodules
** More [[benign]] thyroid nodules
** Multifocal disease
** Multifocal disease
** A higher rate of locoregional recurrence
** A higher rate of locoregional recurrence
Line 158: Line 174:
==== The most important genetic mutations associated with thyroid neoplasia development ====
==== The most important genetic mutations associated with thyroid neoplasia development ====
{| class="wikitable"
{| class="wikitable"
!Oncogenes and growth factors
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Oncogenes and growth factors
!Gene mechanism
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Gene mechanism
!Mutation effect
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Mutation effect
!Neoplasia
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Neoplasia
|-
|-
!''N&H ras''
!''N&H [[Ras oncogene|ras]]''
|
|
* Ras-constitutively bound to GTPase-activating protein (GAP)
* [[Ras oncogene|Ras]]-constitutively bound to [[GTPase activating protein|GTPase-activating protein]] (GAP)
|
|
* Activation of adenylate cyclase and calcium channels
* Activation of [[adenylate cyclase]] and [[calcium]] channels
|
|
* Adenomas
* [[Adenomas]]
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* [[Follicular carcinoma of the Thyroid|Follicular carcinoma]]
* [[Follicular carcinoma of the Thyroid|Follicular carcinoma]]
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
|-
|-
!RET
![[RET proto-oncogene|RET]]
|
|
* Encodes a receptor for glial-derived neurotrophic GF
* Encodes a receptor for glial-derived neurotrophic GF
* Fusion proteins with constitutive thyrosine kinase activities
* Fusion proteins with constitutive thyrosine [[kinase]] activities
* Dimerization of RET thyrosine kinase receptors (TRK)
* Dimerization of RET thyrosine kinase receptors (TRK)
|
|
* Mitogenic through constitutive activation of TKR
* [[Mitogenic]] through constitutive activation of TKR
* Increased auto-phosphorylation and alteration of substrate specificity
* Increased auto-[[phosphorylation]] and alteration of substrate specificity
|
|
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* MEN 2A
* [[MEN 2a|MEN 2A]]
* FMTC
* FMTC
* MEN 2B
* [[MEN 2B]]
|-
|-
!gsp
!Gsp
|
|
* Ribosylated GS-α at arginine 201
* Ribosylated GS-α at [[arginine]] 201
|
|
* Impairing of GTPase activity
* Impairing of [[GTPase]] activity
|
|
* Hot adenomas
* Hot adenomas
|-
|-
!c-MET (α and β subunit)
![[C-MET]] (α and β subunit)
|
|
* Increased receptors for HGF/SF
* Increased receptors for HGF/SF
|
|
* Enhancement of receptor kinase activity
* Enhancement of receptor [[kinase]] activity
|
|
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
|-
|-
!TRK
![[TRK]]
|
|
* Receptor for nerve growth factor
* Receptor for [[nerve]] [[growth factor]]
|
|
* Mitogen activated TK cascade
* Mitogen activated TK cascade
Line 212: Line 228:
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
|-
|-
!EGF / EGF-R
!EGF / [[EGFR|EGF-R]]
|
|
* Competence factor in cell cycle
* Competence factor in [[cell cycle]]
|
|
* Transition through G0-G1 phase
* Transition through [[G0 phase|G0-G1 phase]]
|
|
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
|-
|-
!p53
![[P53 (protein)|P53]]
|
|
* Lack of activation of p21/Waf l gene expression
* Lack of activation of p21/Waf l [[gene]] expression
|
|
* Loss of regulation at the critical G1 to S phase
* Loss of regulation at the critical [[G1 phase|G1]] to [[S phase]]
|
|
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
* [[Anaplastic carcinoma of the thyroid|Anaplastic carcinoma]]
Line 232: Line 248:


==Associated Conditions==
==Associated Conditions==
*Preoperative serum TSH is an independent risk factor for predicting malignancy in a thyroid nodule, and is associated with: 18160464 23731273
Preoperative [[TSH|serum TSH]] is an independent [[risk factor]] for predicting malignancy in a thyroid nodule, and is associated with:<ref name="pmid18160464">{{cite journal |vauthors=Haymart MR, Repplinger DJ, Leverson GE, Elson DF, Sippel RS, Jaume JC, Chen H |title=Higher serum thyroid stimulating hormone level in thyroid nodule patients is associated with greater risks of differentiated thyroid cancer and advanced tumor stage |journal=J. Clin. Endocrinol. Metab. |volume=93 |issue=3 |pages=809–14 |year=2008 |pmid=18160464 |pmc=2266959 |doi=10.1210/jc.2007-2215 |url=}}</ref><ref name="pmid23731273">{{cite journal |vauthors=McLeod DS, Cooper DS, Ladenson PW, Ain KB, Brierley JD, Fein HG, Haugen BR, Jonklaas J, Magner J, Ross DS, Skarulis MC, Steward DL, Maxon HR, Sherman SI |title=Prognosis of differentiated thyroid cancer in relation to serum thyrotropin and thyroglobulin antibody status at time of diagnosis |journal=Thyroid |volume=24 |issue=1 |pages=35–42 |year=2014 |pmid=23731273 |pmc=3887423 |doi=10.1089/thy.2013.0062 |url=}}</ref>
**Higher differentiated thyroid cancer stage
*Higher differentiated [[thyroid cancer]] stage
**Gross extrathyroidal extension
*Gross extrathyroidal extension
**Neck node metastases
*[[Neck]] [[Lymph node|node]] [[metastases]]
 
==Gross Pathology==
==Gross Pathology==
** On gross pathology, cystic lesions, multiple or a single nodule, and encapsulated lesions are themost important and prevalent characteristic findings of thyroid nodules.
* On [[gross pathology]], cystic lesions, multiple or a single nodule, and encapsulated lesions are the most important and prevalent characteristic findings of thyroid nodules.
** On gross pathology, follicular thyroid adenoma may present as a big lesion with thick capsule
* On [[gross pathology]], [[follicular thyroid adenoma]] may present as a big lesion with thick capsule.
Microscopic pathology
 
4071393
 
19888858
 
27078145


19888858
== Microscopic Pathology ==
Diagnostic speciemen feature: the presence of at least six follicular cell groups, each containing 10–15 cells derived from at least two aspirates of a nodule<ref name="pmid4071393">{{cite journal |vauthors=Walfish PG, Strawbridge HT, Rosen IB |title=Management implications from routine needle biopsy of hyperfunctioning thyroid nodules |journal=Surgery |volume=98 |issue=6 |pages=1179–88 |year=1985 |pmid=4071393 |doi= |url=}}</ref><ref name="pmid19888858">{{cite journal |vauthors=Cibas ES, Ali SZ |title=The Bethesda System for Reporting Thyroid Cytopathology |journal=Thyroid |volume=19 |issue=11 |pages=1159–65 |year=2009 |pmid=19888858 |doi=10.1089/thy.2009.0274 |url=}}</ref><ref name="pmid27078145">{{cite journal |vauthors=Nikiforov YE, Seethala RR, Tallini G, Baloch ZW, Basolo F, Thompson LD, Barletta JA, Wenig BM, Al Ghuzlan A, Kakudo K, Giordano TJ, Alves VA, Khanafshar E, Asa SL, El-Naggar AK, Gooding WE, Hodak SP, Lloyd RV, Maytal G, Mete O, Nikiforova MN, Nosé V, Papotti M, Poller DN, Sadow PM, Tischler AS, Tuttle RM, Wall KB, LiVolsi VA, Randolph GW, Ghossein RA |title=Nomenclature Revision for Encapsulated Follicular Variant of Papillary Thyroid Carcinoma: A Paradigm Shift to Reduce Overtreatment of Indolent Tumors |journal=JAMA Oncol |volume=2 |issue=8 |pages=1023–9 |year=2016 |pmid=27078145 |pmc=5539411 |doi=10.1001/jamaoncol.2016.0386 |url=}}</ref><ref name="pmid19888858">{{cite journal |vauthors=Cibas ES, Ali SZ |title=The Bethesda System for Reporting Thyroid Cytopathology |journal=Thyroid |volume=19 |issue=11 |pages=1159–65 |year=2009 |pmid=19888858 |doi=10.1089/thy.2009.0274 |url=}}</ref>
{| class="wikitable"
{| class="wikitable"
! colspan="2" rowspan="2" |Cytology classification
! colspan="2" rowspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |[[Cytology]] classification
! rowspan="2" |Also referred to as:
! rowspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |Also referred to as:
! colspan="2" |Efficient diagnosis
! colspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |Efficient diagnosis
! rowspan="2" |May be seen in:
! rowspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |May be seen in:
! rowspan="2" |FNA cytology
! rowspan="2" align="center" style="background:#4479BA; color: #FFFFFF;" + |FNA cytology
|-
|-
!FNA
! align="center" style="background:#4479BA; color: #FFFFFF;" + |<small>FNA</small>
!Surgical biopsy
! align="center" style="background:#4479BA; color: #FFFFFF;" + |<small><small><small>Surgical biopsy</small></small></small>
|-
|-
| rowspan="5" |Follicular lesions 
! rowspan="5" |Follicular lesions 
|Benign (macrofollicular)
![[Benign]] (macrofollicular)
|
|
* Adenomatoid adenoma
* Adenomatoid [[adenoma]]
* Hyperplastic adenoma
* [[Hyperplastic]] [[adenoma]]
* Colloid adenoma
* Colloid [[adenoma]]
| +
| +
|
|
|
|
*Normal thyroid tissue
*Normal [[Thyroid Gland|thyroid]] [[Tissue (biology)|tissue]]
*Sporadic nodular goiter
*Sporadic nodular [[goiter]]
*Monoclonal macrofollicular tumors
*[[Monoclonal]] macrofollicular tumors
*Hyperplastic nodules
*[[Hyperplasia|Hyperplastic]] nodules
*Colloid adenomas (most common)
*Colloid adenomas (most common)
|
|
*May have areas of cystic degeneration with cellular debris and hemosiderin-laden macrophages
*May have areas of cystic degeneration with cellular debris and [[hemosiderin]]-laden [[macrophages]]
*Cellular characteristics:
*[[Cellular]] characteristics:
**Small and flat
**Small and flat
**Uniform in size
**Uniform in size
Line 281: Line 292:
**Follicle size may vary, with a few microfollicles interspersed among the macrofollicles, especially if the sample was obtained from an area close to the capsule of the lesion
**Follicle size may vary, with a few microfollicles interspersed among the macrofollicles, especially if the sample was obtained from an area close to the capsule of the lesion
*Colloid:
*Colloid:
**May smear across the slide or occasionally aggregated into droplets due to disruption of follicles during FNA
**May smear across the slide or occasionally aggregated into droplets due to disruption of follicles during [[FNA]]
**Stains blue on a Papanicolaou stain
**Stains blue on a [[Papanicolaou smear|Papanicolaou]] stain
**May be abundant in the background of macrofollicular lesions
**May be abundant in the background of macrofollicular lesions
|-
|-
|Follicular neoplasm/microfollicular 
![[Follicular neoplasm of thyroid|Follicular neoplasm]]/microfollicular 
|
|
* Cellular adenoma
* [[Cellular]] [[adenoma]]
* Indeterminate adenoma
* Indeterminate [[adenoma]]
* Trabecular adenoma
* Trabecular [[adenoma]]
|
|
| +
| +
|
|
* Follicular adenomas
* Follicular [[adenomas]]
* Follicular carcinomas
* Follicular [[carcinomas]]
* Follicular variant of papillary cancer
* Follicular variant of [[Papillary carcinoma of the thyroid|papillary cancer]]
* Occasionally from autonomously functioning thyroid nodules
* Occasionally from autonomously functioning thyroid nodules
|
|
Line 306: Line 317:
* Follicular carcinoma:
* Follicular carcinoma:
** Focal microscopic invasion
** Focal microscopic invasion
* Cellular or trabecular adenomas:
* [[Cellular]] or trabecular adenomas:
** Lesions with less definite or no follicle formation
** Lesions with less definite or no follicle formation
** May show vascular or capsule invasion
** May show vascular or capsule invasion
|-
|-
|Follicular lesion of undetermined significance (FLUS)
!Follicular lesion of undetermined significance (FLUS)
| rowspan="2" |
| rowspan="2" |
| rowspan="2" | +
| rowspan="2" | +
| rowspan="2" |
| rowspan="2" |
| rowspan="2" |
| rowspan="2" |
* Commonly, especially in nodular goiters
* Commonly, especially in nodular [[goiters]]
| rowspan="2" |
| rowspan="2" |
* FLUS:
* FLUS:
** the lesion has approximately equal number of macrofollicular fragments and microfollicles
** The lesion has approximately equal number of macrofollicular fragments and microfollicles
* AUS:
* AUS:
** cells with mild nuclear atypia
** [[Cells (biology)|Cells]] with mild [[nuclear]] atypia
* Mostly due to compromised speciemens:
* Mostly due to compromised speciemens:
** Poor fixation or obscuring blood (FLUS)
** Poor fixation or obscuring [[blood]] (FLUS)
|-
|-
|Atypia of undetermined significance (AUS)
!Atypia of undetermined significance (AUS)
|-
|-
|Hürthle cells 
![[Hurthle cells|Hürthle cells]] 
|
|
* Oncocytes
* Oncocytes
* Askanazy cells
* Askanazy cells
* Oxyphil cells
* [[Oxyphil cell|Oxyphil cells]]
| +
| +
|
|
|
|
* Focal Hürthle-cell change:
* Focal [[Hurthle cell carcinoma|Hürthle-cell]] change:
** Degenerating macrofollicular lesions
** Degenerating macrofollicular lesions
** Hashimoto's thyroiditis
** [[Hashimoto's thyroiditis]]
|
|
* Large polyclonal cells
* Large [[polyclonal]] [[Cells (biology)|cells]]
* Oxyphil cytoplasm
* [[Oxyphil cell|Oxyphil]] [[cytoplasm]]
* Considered benign if there is no evidence of vascular or capsular invasion
* Considered [[benign]] if there is no evidence of [[vascular]] or capsular invasion
* Considered malignant if invasion is present
* Considered [[malignant]] if invasion is present
** Hürthle-cell cancer
** [[Hurthle cell carcinoma|Hürthle-cell]] [[cancer]]
** Follicular cancer
** [[Follicular cancer of the thyroid|Follicular cancer]]
** Oxyphil cell type cancer
** [[Oxyphil cell]] type [[cancer]]
|-
|-
| colspan="2" |Papillary cancer
! colspan="2" |[[Papillary thyroid cancer|Papillary cancer]]
|
|
* The follicular variant of papillary cancer
* The follicular variant of papillary cancer
|
|
| +
| +
|Epithelioid giant cells  
|[[Epithelioid]] [[giant cells]]
*Papillary cancer
*[[Papillary thyroid cancer|Papillary cancer]]
*Degenerating areas of macrofollicular nodules
*Degenerating areas of macrofollicular nodules
*Subacute granulomatous thyroiditis  
*[[Subacute granulomatous thyroiditis]]
Psammoma bodies
[[Psammoma body|Psammoma bodies]]
* Papillary carcinoma
* [[Papillary carcinoma of the thyroid|Papillary carcinoma]]
* Benign thyroid lesions
* [[Benign]] [[Thyroid Gland|thyroid]] lesions
|
|
*Large cells and nuclei 
*Large [[Cells (biology)|cells]] and [[nuclei]] 
*Ground glass appearance of cytoplasm 
*Ground glass appearance of [[cytoplasm]] 
*Nuclei appearance:
*[[Nuclei]] appearance:
**Clefts 
**Clefts 
**Grooves 
**Grooves 
**Holes 
**Holes 
**Intranuclear cytoplasmic inclusions = Orphan Annie eyes 
**Intranuclear [[cytoplasmic]] inclusions = Orphan Annie eye
**Small nucleoli 
**Small [[nucleoli]] 
*Psammoma bodies
*Psammoma bodies
**Small laminated calcifications
**Small laminated calcifications
*Sticky colloid  
*Sticky colloid  
**Colloid "stick" to debris and cell clusters, instead of smearing across the slide
**Colloid "stick" to debris and cell clusters, instead of smearing across the slide
*Epithelioid giant cells  
*[[Epithelioid]] [[giant cells]]
**Can also be seen in:
**Can also be seen in:
***Degenerating areas of macrofollicular nodules
***Degenerating areas of macrofollicular nodules
***Subacute granulomatous thyroiditis  
***[[Subacute granulomatous thyroiditis]]
|-
|-
| colspan="2" |Medullary cancer 
! colspan="3" |[[Medullary carcinoma of thyroid|Medullary cancer]] 
|
|
|
| +
| +
Line 384: Line 394:
|
|
*Spindle-shaped cells
*Spindle-shaped cells
*Frequently pleomorphic cells without follicle development
*Frequently [[pleomorphic]] [[Cells (biology)|cells]] without follicle development
*Supporting stroma may frequently stains for amyloid
*Supporting [[stroma]] may frequently stains for [[amyloid]]
*Red cytoplasmic granules
*Red [[cytoplasmic]] granules
*Eccentrically placed nuclei
*Eccentrically placed [[nuclei]]
*Slightly granular Cytoplasm that may be configured as a tear drop or cytoplasmic tail  
*Slightly granular [[cytoplasm]] that may be configured as a tear drop or [[cytoplasmic]] tail  
|-
|-
| colspan="2" |Anaplastic thyroid cancer
! colspan="3" |[[Anaplastic thyroid cancer]]
|
| +
| +
Large needle biopsy if needed
|
|
|
|
* Anaplastic thyroid cancer
* [[Anaplastic thyroid cancer]]
|
|
* Spindle cells
* [[Spindle cells]]
* Pleomorphic giant cell
* Pleomorphic [[giant cell]]
* Squamoid
* Squamoid
* Mitosis
* [[Mitosis]]
** Numerous mitotic figures
** Numerous [[mitotic]] figures
** Atypical mitoses
** Atypical [[mitoses]]
* Extensive necrosis.
* Extensive [[necrosis]]
|}
 
*Both [[polyclonal]] and [[monoclonal]] nodules appear similar on [[fine needle aspiration]] (FNA) (macrofollicular) and are [[benign]]
*The diagnosis of [[Follicular cancer of the thyroid|follicular cancer]] can not be made based on [[FNA]], because vascular or capsular invasion is required to make the diagnosis of [[Follicular cancer of the thyroid|follicular cancer]]. 8420446
 
 
==== Neoplastic thyroid nodules subclassification microscopic pathology: ====
{| class="wikitable"
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Neoplasm
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Subclass
! align="center" style="background:#4479BA; color: #FFFFFF;" + |Features
!
|-
| rowspan="4" |Follicular [[Thyroid Gland|thyroid]] lesions
|Minimally invasive [[follicular carcinoma]]
|
* Only invasion of the capsule of the [[tumor]] without [[vascular]] invasion
|
|-
|Widely invasive [[follicular carcinoma]]
|
*Extensive invasion of the [[tumor]] capsule
*A multinodular [[tumor]] without a well-defined capsule invading the normal [[Thyroid Gland|thyroid]] surrounding the [[tumor]]
*Extensive [[vascular]] invasion (>4 foci of angioinvasion)
|
|-
|Encapsulated follicular variant of [[papillary thyroid cancer]]
| rowspan="2" |
* Minor [[vascular]] invasion (≤4 foci of angioinvasion within the [[tumor]] or capsule of the [[tumor]]) with or without capsular invasion
|
|-
|Infiltrative variant of [[papillary thyroid cancer]]
|
|-
| rowspan="8" |[[Papillary thyroid cancer]]
|Tall cell variant
|
* [[Tumor]] [[Cells (biology)|cells]] with [[eosinophilic]] [[cytoplasm]] that are twice as tall as they are wide
* The primary [[Tumor|tumors]] tend to be large 
* Often invasive, that many patients have both local and distant [[metastases]] at the time of diagnosis 
|
|-
|Insular varient
|
* Solid nests of tumor, often separated by fibrous bands, but the [[tumor cell]] nuclei have the same characteristics as do the [[nuclei]] of classical [[Papillary carcinoma of the thyroid|papillary cancers]]
|
|-
|Columnar variant
|
* Elongated cells with palisading [[nuclei]]
|
|-
|[[Hurthle cell carcinoma|Hürthle]] or [[Hurthle cell carcinoma|oxyphilic]] variant
|
* Cellular features of [[Hurthle cell carcinoma|Hürthle cell carcinomas]] but cells that are arranged in papillary formations.
|
|-
|Clear cell variant
|
* Clear cell view with clear [[cytoplasm]]
* Must be distinguished from [[Clear cell tumor|clear cell carcinomas]] of other organs such as the [[kidney]] or [[colon]] that have [[metastasized]] to the [[thyroid]]
|
|-
|Diffuse sclerosing variant
|
* Diffuse involvement of the [[thyroid]]
* Stromal [[fibrosis]]
* Prominent [[lymphocytic]] infiltration
|
|-
|Cribriform morular variant
|
* Prominent [[cribriform]] pattern with solid and [[Spindle cells|spindle cell]] areas as well as [[squamous]] morules
* Often associated with [[familial adenomatous polyposis]]
|
|-
|Hobnail variant
|
* Multifocal with variably sized complex papillary structures lined by [[Cells (biology)|cells]]
* [[Cells (biology)|Cells]] with increased [[nuclear]] to [[Cytoplasm|cytoplasmatic]] ratios
* Apically placed [[nuclei]] that lead to a surface bulge (hobnail appearance)
*: 19956062
|
|}
|}


==Microscopic Pathology==
*Both polyclonal and monoclonal nodules appear similar on fine needle aspiration (FNA) (macrofollicular) and are benign 8426623
*The diagnosis of follicular cancer can not be made based on FNA, because vascular or capsular invasion is required to make the diagnosis of follicular cancer. 8420446
==References==
==References==
{{reflist|2}}
{{reflist|2}}

Latest revision as of 15:35, 3 November 2017


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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Thyroid nodules may arise from different cells in the thyroid parenchyma. The pathogenesis of developing a thyroid nodule may differ based on the type of the nodule, and whether it is malignant or benign. Basically thyroid nodules may develop secondary to hyperplasia, mutations and resultant carcinoma, excess colloid accumulation, or frominflammation of thyroid tissue. Genetic mutation is considered as one of the most important mechanisms of developing thyroid nodules, especially neoplastic thyroid nodules. Most of these mutations occur as somatic mutations, while some may exhibit familial inheritance. The most important variety of familial thyroid cancers are caused by genetic mutations, and are called familial non-medullary thyroid cancer (FNMTC). Other important genes related to thyroid nodule formation include, N&H ras, RET, Gsp, C-MET, TRK, EGF / EGF-R, and P53.

Pathogenesis

A summary of thyroid nodule pathophysiology is presented in the slides below: [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][6][19][20][21][22][23][24][25][26][27][28][29][30][31]

(a) Hyperplastic nodules

1. TSH role in thyroid nodule formation

2. Thyroid overgrowth stimulants:

Thyroid normally has a low proliferative activity, although it can start proliferation rapidly in response to certain stimulants. Stimulants mainly act through TSH mediated activity and production. The following stimulants appear to have the most important role in pathogenesis of hyperplastic nodules:[32][33]

3. Hyperplasia development phase:
4. Neoplasia development phase:
  • Each follicle is composed of different clones of cells (polyclonal), but during nodule formation they replicate in a simultaneous and coordinated manner, so each follicle of the nodule reproduces the same heterogeneity of the mother follicle.
  • When a neoplasm arises in the nodule, then the neoplastic follicle shows a monoclonal pattern, suggesting that cancer arises from a single cell
  • Activation of oncogenes is considered the underlying event leading to uncontrolled cell growth.

(b) Neoplastic nodules

Papillary thyroid carcinoma

Abbrevaitions:

ERK: extracellular signal-regulated kinase; MAPK: mitogen-activated protein kinase

(c) Colloid and cystic nodules

1. Colloid nodules

  • The colloid nodules consist of colloid droplets and thyroglobulin vesicles.
  • Thyroid gland keeps a balance between colloid and thyroglobulin production by regulating the secretion of thyroglobulin into colloid and reabsorption of colloid into thyroid follicular cells. This regulation is maintained by macro-pinocytosis (pseudopods) and micro-pinocytosis (microvilli).
  • Any imbalance between secretion and reabsorption of thyroglobulin leads to a disruption of the equilibrium, and produces a colloid appeared thyroid nodule. These nodules may also be produced as a defect of intraluminal thyroglobulin reabsorption. 

2. Iodine related nodules pathogenesis:

Iodine excess can lead to colloid nodules in thyroid gland, leading to a colloid goitre:

Another mechanism that may lead to colloid goitre formation is loss of thyroglobulin packaging ability, that may lead to an enormous enlargement of the follicles and flattening of the epithelium.

3. Cystic thyroid nodules

Cystic thyroid nodules may be classified into the following types:

(d) Thyroiditic nodule

Nodular lymphocytic thyroiditis almost always present in combination with other thyroiditic diseases. They can also present as a part of infection. It has been shown that the ability of super-antigens (SAgs) to activate the immune system may play a role in the course of autoimmune disorders. In most of these cases, the mechanism of nodular lesion is the same as the mechanism of the main disease, implying that the thyroid nodule is a part of normal disease pattern. Many of these nodules are not identifiable based on physical exam, and are detected during thyroid scintigraphy. The most important thyroiditic diseases that may present as lymphocytic nodular thyroid are:

Genetics

Genetic mutation is considered as one of the most important mechanisms of developing thyroid nodules, especially neoplastic thyroid nodules. Most of these mutations occur as somatic mutations, while some may occur in a familial order. The most important category of familial thyroid cancers are due to genetic mutations, and are called familial non-medullary thyroid cancer (FNMTC), with the following features:

The most important genetic mutations associated with thyroid neoplasia development

Oncogenes and growth factors Gene mechanism Mutation effect Neoplasia
N&H ras
RET
  • Encodes a receptor for glial-derived neurotrophic GF
  • Fusion proteins with constitutive thyrosine kinase activities
  • Dimerization of RET thyrosine kinase receptors (TRK)
Gsp
  • Hot adenomas
C-MET (α and β subunit)
  • Increased receptors for HGF/SF
  • Enhancement of receptor kinase activity
TRK
  • Mitogen activated TK cascade
EGF / EGF-R
P53
  • Lack of activation of p21/Waf l gene expression
  • Loss of regulation at the critical G1 to S phase

Associated Conditions

Preoperative serum TSH is an independent risk factor for predicting malignancy in a thyroid nodule, and is associated with:[42][43]

Gross Pathology

Microscopic Pathology

Diagnostic speciemen feature: the presence of at least six follicular cell groups, each containing 10–15 cells derived from at least two aspirates of a nodule[44][45][46][45]

Cytology classification Also referred to as: Efficient diagnosis May be seen in: FNA cytology
FNA Surgical biopsy
Follicular lesions  Benign (macrofollicular) +
  • May have areas of cystic degeneration with cellular debris and hemosiderin-laden macrophages
  • Cellular characteristics:
    • Small and flat
    • Uniform in size
    • Non-crowded
    • Smeared colloid is seen in the background
    • Follicle size may vary, with a few microfollicles interspersed among the macrofollicles, especially if the sample was obtained from an area close to the capsule of the lesion
  • Colloid:
    • May smear across the slide or occasionally aggregated into droplets due to disruption of follicles during FNA
    • Stains blue on a Papanicolaou stain
    • May be abundant in the background of macrofollicular lesions
Follicular neoplasm/microfollicular  +
  • Well-developed microfollicles
  • Crowding of cells
    • May form clusters and clumps
  • Scant colloid
  • Varying nuclear atypia
  • Varying cellular pleomorphism
  • Follicular carcinoma:
    • Focal microscopic invasion
  • Cellular or trabecular adenomas:
    • Lesions with less definite or no follicle formation
    • May show vascular or capsule invasion
Follicular lesion of undetermined significance (FLUS) +
  • Commonly, especially in nodular goiters
  • FLUS:
    • The lesion has approximately equal number of macrofollicular fragments and microfollicles
  • AUS:
  • Mostly due to compromised speciemens:
    • Poor fixation or obscuring blood (FLUS)
Atypia of undetermined significance (AUS)
Hürthle cells  +
Papillary cancer
  • The follicular variant of papillary cancer
+ Epithelioid giant cells

Psammoma bodies

Medullary cancer  +
  • Medullary cancer
Anaplastic thyroid cancer +


Neoplastic thyroid nodules subclassification microscopic pathology:

Neoplasm Subclass Features
Follicular thyroid lesions Minimally invasive follicular carcinoma
  • Only invasion of the capsule of the tumor without vascular invasion
Widely invasive follicular carcinoma
  • Extensive invasion of the tumor capsule
  • A multinodular tumor without a well-defined capsule invading the normal thyroid surrounding the tumor
  • Extensive vascular invasion (>4 foci of angioinvasion)
Encapsulated follicular variant of papillary thyroid cancer
  • Minor vascular invasion (≤4 foci of angioinvasion within the tumor or capsule of the tumor) with or without capsular invasion
Infiltrative variant of papillary thyroid cancer
Papillary thyroid cancer Tall cell variant
Insular varient
Columnar variant
  • Elongated cells with palisading nuclei
Hürthle or oxyphilic variant
Clear cell variant
Diffuse sclerosing variant
Cribriform morular variant
Hobnail variant
  • Multifocal with variably sized complex papillary structures lined by cells
  • Cells with increased nuclear to cytoplasmatic ratios
  • Apically placed nuclei that lead to a surface bulge (hobnail appearance)
    19956062

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