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{{Thyroid nodule}}
{{Thyroid nodule}}
{{CMG}}; {{AE}} {{MIR}}
{{CMG}}; {{AE}} {{MIR}}
==== Bethesda System for Reporting Thyroid Cytopathology ====
 
<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>
== Overview ==
{| class="wikitable"
There are various methods for classifying a thyroid nodule. A method has been developed by the [[National Cancer Institute|National Cancer Institute (NCI)]] to address terminology and other issues related to [[thyroid]] [[Fine-needle aspiration|fine-needle aspiration (FNA)]], called "The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)". The other classification method is the [[TNM classification|TNM classification (tumor-node-metastasis) method]] developed by the [[American Joint Committee on Cancer]] and the International Union against Cancer focused on [[prognosis]] has been established to avoid heterogeneity of prognostic classification schemes used for differentiated [[Thyroid cancer|thyroid cancers]]. Thyroid nodules may also be classified based on their [[ultrasound]] properties according to the TIRAD classification method, which has been proposed by Horvath et al, with a modified recommendation from Jin Kwak et al, and finally, thyroid nodules may also be classified on the basis of origin.
!classification
== Classification ==
!FNA cytology
 
!Predicted risk of malignancy
 
{{familytree/start}}
{{familytree | | | | | | | | B01 | | | | |B01=Thyroid nodule classification}}
{{familytree | | |,|-|-|-|-|-|+|-|-|-|-|-|.| }}
{{familytree | | C01 | | | | |!| | | | | C03 |C01= '''Bethesda classification system''' |C03= '''TIRAD classification system'''}}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | | C01 | | | | |!| | | | | C03 |C01= Based on thyroid [[cytopathology]] |C03= Based on [[Ultrasound|sonographic]] features}}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | boxstyle=text-align: left; | | C01 | | | | |!| | | | | C03 |C01= •[[Benign]] <br> •Nondiagnostic or Unsatisfactory <br> •Follicular lesion of undetermined significance <br> •[[Atypia]] of undetermined significance <br> •Follicular neoplasm <br> •Suspicious for a follicular neoplasm <br> •[[Malignant]] <br> | C03= •TIRADS 1=Normal [[thyroid gland]] <br> •TIRADS 2=[[Benign]] lesions <br> •TIRADS 3=Probably [[benign]] lesions <br> •TIRADS 4= Contain 1-4 suspicious features <br> •TIRADS 5=Contain all five suspicious features <br> •TIRADS 6=Biopsy proven [[malignancy]]}}
{{familytree | | | | | | | | C02 | | | | | | | C02= Differentiated and anaplastic thyroid carcinoma }}
{{familytree | | | | |,|-|-|-|^|-|-|-|.| | | }}
{{familytree | | | | F01 | | | | | | F02 | | | | F01 = '''TNM staging AJCC UICC 2017''' |  F02 = '''Classification based on their origin'''}}
{{familytree | | | | |!| | | | | |,|-|^|-|.| | | | }}
{{familytree | boxstyle=text-align: left; | | | | F01 | | | X01 | | | | X02 | | | F01 =  •Primary tumor (T) <br> •Regional [[lymph node|lymph nodes]] (N) <br> •Distant [[metastasis]] (M) | X01 = Nonmedullary (epithelial) [[thyroid cancers]] (NMTCs) <br> •Papillary cell tumors <br> •Follicular tumors <br> •Hurthle cell tumors <br> •Anaplastic tumors | X02 = Medullary thyroid cancers }}
{{familytree/end}}
 
== The Bethesda System For Reporting Thyroid Cytopathology ==
To address terminology and other issues related to thyroid [[Fine-needle aspiration|fine-needle aspiration (FNA)]], the [[National Cancer Institute|National Cancer Institute (NCI)]] developed a new classification method called "The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)".<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>
{|
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Classification
! style="background:#4479BA; color: #FFFFFF;" align="center" + |FNA cytology
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Predicted risk of malignancy
|-
|-
|Benign
! style="background:#DCDCDC;" align="center" + |[[Benign]]
|
| style="background:#F5F5F5;" + |
* Macrofollicular
* Macrofollicular
* Adenomatoid/hyperplastic nodules
* [[Adenomatoid tumor|Adenomatoid]]/[[Hyperplasia|hyperplastic]] nodules
* Colloid adenomas (most common)
* Colloid [[adenomas]] (most common)
* Nodular goiter
* Nodular [[goiter]]
* Lymphocytic thyroiditis
* [[Lymphocytic thyroiditis]]
* Granulomatous thyroiditis
* [[Granulomatous thyroiditis]]
|0–3 %
| style="background:#F5F5F5;" align="center" + |0–3 %
|-
|-
|Nondiagnostic or Unsatisfactory
! style="background:#DCDCDC;" align="center" + |Nondiagnostic or unsatisfactory
|
| style="background:#F5F5F5;" align="center" + | ---
|1–4 %
| style="background:#F5F5F5;" align="center" + |1–4 %
|-
|-
|Follicular lesion of undetermined significance
! style="background:#DCDCDC;" align="center" + | Follicular lesion of undetermined significance
|
| style="background:#F5F5F5;" + |
* Mixed macro- and microfollicular nodules
* Mixed macro- and microfollicular nodules
| rowspan="2" |5–15 %
| rowspan="2" style="background:#F5F5F5;" align="center" + |5–15 %
|-
|-
|Atypia of undetermined significance
! style="background:#DCDCDC;" align="center" + | [[Atypia]] of undetermined significance
|
| style="background:#F5F5F5;" + |
* Atypical cells
* [[Atypia|Atypical cells]]
|-
|-
|Follicular neoplasm
! style="background:#DCDCDC;" align="center" + |[[Follicular thyroid cancer|Follicular neoplasm]]
|
| style="background:#F5F5F5;" + |
* Microfollicular nodules
* Microfollicular nodules
** Hurthle cell lesions
* [[Hurthle cell carcinoma|Hurthle cell lesions]]
|15–30 %
| style="background:#F5F5F5;" align="center" + |15–30 %
|-
|-
|Suspicious for a follicular neoplasm
! style="background:#DCDCDC;" align="center" + |Suspicious for a [[Follicular thyroid cancer|follicular neoplasm]]
|
| style="background:#F5F5F5;" + |
* Suspicious for Hurthle cell neoplasm
* Suspicious for [[Hurthle cell carcinoma|Hurthle cell neoplasm]]
|60–75 %  
| style="background:#F5F5F5;" align="center" + |60–75 %  
|-
|-
|Malignant
! style="background:#DCDCDC;" align="center" + | [[Malignant]]
|
| style="background:#F5F5F5;" + |
* PTC (most common)
* [[Papillary thyroid cancer|PTC]] (most common)
* MTC
* [[Medullary thyroid cancer|MTC]]
* Anaplastic carcinoma
* [[Anaplastic thyroid cancer|Anaplastic carcinoma]]
* High-grade metastatic cancers
* High-grade [[Metastatic cancer|metastatic cancers]]
|97–99 %
| style="background:#F5F5F5;" align="center" + |97–99 %
|}
|}
==== Classification of neoplastic thyroid nodules based on their origin: ====
'''Abbreviations''': '''PTC'''- ''[[Papillary thyroid carcinoma]]'', '''MTC'''- ''[[Medullary thyroid cancer|Medullary thyroid carcinoma]]''
{| class="wikitable"
 
!
==Classification Based On TNM Staging==
!
The [[TNM classification|TNM classification (tumor-node-metastasis)]] was adopted by the [[American Joint Committee on Cancer]] and the International Union against Cancer more than 10 years ago. This classification system mainly focuses on [[prognosis]] and is developed to avoid heterogeneity of [[prognostic]] classification schemes used for differentiated [[thyroid cancers]].<ref name="pmid9360506">{{cite journal |vauthors=Loh KC, Greenspan FS, Gee L, Miller TR, Yeo PP |title=Pathological tumor-node-metastasis (pTNM) staging for papillary and follicular thyroid carcinomas: a retrospective analysis of 700 patients |journal=J. Clin. Endocrinol. Metab. |volume=82 |issue=11 |pages=3553–62 |year=1997 |pmid=9360506 |doi=10.1210/jcem.82.11.4373 |url=}}</ref>
!Origin
 
!histologic subtypes
==== Differentiated and anaplastic thyroid carcinoma TNM staging AJCC UICC 2017 ====
!
{|
|-
|-
| rowspan="4" |Nonmedullary thyroid cancers (NMTCs)
! colspan="9" style="background:#4479BA; color: #FFFFFF;" align="center" + |Papillary, follicular, poorly differentiated, Hurthle cell and anaplastic thyroid carcinoma
| rowspan="4" |95% of tumors
| rowspan="4" |thyroid epithelial cells
|papillary (85%)
|95% are sporadic tumors
5% may be related to inherited genetics due to familial origin
* Classic varient
* tall cell variant
* insular varient
* columnar variant
* Hürthle or oxyphilic variant
* solid or trabecular variant
* clear cell variant
* diffuse sclerosing variant
* cribriform morular variant
* hobnail variant
|-
|-
|follicular (11%)
! colspan="5" style="background:#4479BA; color: #FFFFFF;" align="center" + |Primary tumor (T)
|
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Regional lymph nodes (N)
* Benign follicular adenoma
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Distant metastasis (M)
* Minimally invasive follicular carcinoma
* Widely invasive follicular carcinoma
* Encapsulated follicular variant of papillary thyroid cancer
* Infiltrative variant of papillary thyroid cancer
|-
|-
|Hürthle cell (3%)
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''T category'''
|
! colspan="4" style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''T criteria'''
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''N category'''
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''N criteria'''
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''M category'''
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''M criteria'''
|-
|-
|anaplastic (1%)
! style="background:#DCDCDC;" align="center" + |TX
|
| colspan="4" style="background:#F5F5F5;" + |Primary [[tumor]] cannot be assessed
! style="background:#DCDCDC;" align="center" + |NX
| style="background:#F5F5F5;" + |Regional [[Lymph node|lymph nodes]] cannot be assessed
! style="background:#DCDCDC;" align="center" + |M0
| style="background:#F5F5F5;" + |No distant [[metastasis]]
|-
|-
|Medullary thyroid cancers (MTCs)
! style="background:#DCDCDC;" align="center" + |T0
|5% of all thyroid malignancies
| colspan="4" style="background:#F5F5F5;" + |No evidence of primary [[tumor]]
|calcitonin-producing parafollicular cells
! style="background:#DCDCDC;" align="center" + |N0
|
| style="background:#F5F5F5;" + |No evidence of locoregional [[lymph node]] [[metastasis]]
|20% they are familial and occur as part of the multiple endocrine neoplasia (MEN) syndromes
! style="background:#DCDCDC;" align="center" + |M1
|}
| style="background:#F5F5F5;" + |Distant [[metastasis]]
Of the differentiated cancers, papillary cancer comprises about 85% of cases compared to about 10% that have follicular histology, and 3% that are Hu¨rthle cell or oxyphil tumors
 
==== Neoplastic thyroid nodules subclassification: ====
{| class="wikitable"
!Neoplasm
!Subclass
!Features
!
|-
|-
| rowspan="5" |Follicular thyroid lesions
! style="background:#DCDCDC;" align="center" + |T1
|Benign follicular adenoma
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤2 cm in greatest dimension limited to the [[thyroid]]
|
! style="background:#DCDCDC;" align="center" + |N0a
|
| style="background:#F5F5F5;" + |One or more cytologically or [[histologically]] confirmed [[benign]] [[lymph nodes]]
| colspan="2" rowspan="5" style="background:#F5F5F5;" + |
|-
|-
|Minimally invasive follicular carcinoma
! style="background:#DCDCDC;" align="center" + |T1a
|only invasion of the capsule of the tumor without vascular invasion
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤1 cm in greatest dimension limited to the [[thyroid]]
|
! style="background:#DCDCDC;" align="center" + |N0b
| style="background:#F5F5F5;" + |No [[radiological]] or clinical evidence of local regional [[lymph node metastases]]
|-
|-
|Widely invasive follicular carcinoma
! style="background:#DCDCDC;" align="center" + |T1b
|
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >1 cm but ≤2 cm in greatest dimension limited to the [[thyroid]]
*Extensive invasion of the tumor capsule
! style="background:#DCDCDC;" align="center" + |N1
*A multinodular tumor without a well-defined capsule invading the normal thyroid surrounding the tumor
| style="background:#F5F5F5;" + |[[Metastasis]] to regional [[Lymph nodes|nodes]]
*Extensive vascular invasion (>4 foci of angioinvasion)
|
|-
|-
|Encapsulated follicular variant of papillary thyroid cancer
! style="background:#DCDCDC;" align="center" + |T2
|minor vascular invasion (≤4 foci of angioinvasion within the tumor or capsule of the tumor) with or without capsular invasion
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >2 cm but ≤4 cm in greatest dimension limited to the [[thyroid]]
|
! style="background:#DCDCDC;" align="center" + |N1a
| style="background:#F5F5F5;" + |[[Metastases]] to level VI or VII ([[Pretracheal lymph nodes|pretracheal]], [[Paratracheal lymph nodes|paratracheal]], or [[Prelaryngeal lymph nodes|prelaryngeal/Delphian]], or [[Mediastinal lymph node|upper mediastinal]]) [[lymph nodes]]. This can be unilateral or bilateral disease
|-
|-
|Infiltrative variant of papillary thyroid cancer
! style="background:#DCDCDC;" align="center" + |T3
|
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >4 cm limited to the [[thyroid]], or gross extrathyroidal extension invading only [[Strap muscles of the neck|strap muscles]]
|
! style="background:#DCDCDC;" align="center" + |N1b
| style="background:#F5F5F5;" + |[[Metastasis]] to unilateral, bilateral, or [[contralateral]] [[neck]] [[lymph nodes]] (levels I, II, III, IV, or V) or [[retropharyngeal lymph nodes]]
|-
|-
| rowspan="10" |papillary thyroid cancer
! style="background:#DCDCDC;" align="center" + |T3a
|Classic varient
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >4 cm limited to the [[thyroid]]
|
| colspan="4" rowspan="5" style="background:#F5F5F5;" + |
|
|-
|-
|tall cell variant
! style="background:#DCDCDC;" align="center" + |T3b
|more aggressive tumor than classical papillary cancer
| colspan="4" style="background:#F5F5F5;" + |Gross extrathyroidal extension invading only [[Strap muscles of the neck|strap muscles]] ([[sternohyoid]], [[sternothyroid]], [[thyrohyoid]], or [[Omohyoid muscle|omohyoid muscles]]) from a [[tumor]] of any size
tumor cells with eosinophilic cytoplasm that are twice as tall as they are wide. The primary tumors tend to be large, they are often invasive, and many patients have both local and distant metastases at the time of diagnosis 
|
|-
|-
|insular varient
! style="background:#DCDCDC;" align="center" + |T4
|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 cancers.
| colspan="4" style="background:#F5F5F5;" + |Includes gross extrathyroidal extension
|
|-
|-
|columnar variant
! style="background:#DCDCDC;" align="center" + |T4a
|elongated cells with palisading nuclei.
| colspan="4" style="background:#F5F5F5;" + |Gross extrathyroidal extension invading [[Subcutaneous tissue|subcutaneous soft tissues]], [[larynx]], [[trachea]], [[esophagus]], or [[recurrent laryngeal nerve]] from a [[tumor]] of any size
|
|-
|-
|Hürthle or oxyphilic variant
! style="background:#DCDCDC;" align="center" + |T4b
|Cellular features of Hürthle cell carcinomas but cells that are arranged in papillary formations.
| colspan="4" style="background:#F5F5F5;" + |Gross extrathyroidal extension invading [[prevertebral fascia]] or encasing the [[carotid artery]] or [[mediastinal]] [[Blood vessel|vessels]] from a [[tumor]] of any size
|
|}
 
== Thyroid Nodule Classification Based On Ultrasound Features ==
A classification system has been proposed by Horvath et al, with a modified recommendation from Jin Kwak et al.<ref name="pmid19276237">{{cite journal |vauthors=Horvath E, Majlis S, Rossi R, Franco C, Niedmann JP, Castro A, Dominguez M |title=An ultrasonogram reporting system for thyroid nodules stratifying cancer risk for clinical management |journal=J. Clin. Endocrinol. Metab. |volume=94 |issue=5 |pages=1748–51 |year=2009 |pmid=19276237 |doi=10.1210/jc.2008-1724 |url=}}</ref>
{|
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Ultrasound classification
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Features
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Risk of Malignancy
|-
|-
|solid or trabecular variant
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 1'''
|
| colspan="2" style="background:#F5F5F5;" + |Normal [[thyroid gland]]
|
| style="background:#F5F5F5;" + |
|-
|-
|clear cell variant
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 2'''
|must be distinguished from clear cell carcinomas of other organs such as the kidney or colon that have metastasized to the thyroid.
| style="background:#F5F5F5;" + |[[Benign]] lesions
|
| style="background:#F5F5F5;" + |
* [[Avascular]] anechoic lesion with [[echogenic]] specks (colloid type I)
* [[Vascular]] heteroechoic non-expansile, non-encapsulated [[nodules]] with peripheral halo (colloid type II)
* Isoechoic or heteroechoic, non-encapsulated, expansile [[vascular]] nodules (colloid type III)
| style="background:#F5F5F5;" + |0% risk of malignancy
|-
|-
|diffuse sclerosing variant
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 3'''
|diffuse involvement of the thyroid, stromal fibrosis, and prominent lymphocytic infiltration
| style="background:#F5F5F5;" + |Probably [[Benign|benign lesions]]
|
| style="background:#F5F5F5;" + |
* [[Nodule]] property:
** Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral [[vascularity]], usually in the setting of [[Hashimoto's thyroiditis]]
| style="background:#F5F5F5;" + |<5% risk of malignancy
|-
|-
|cribriform morular variant
! rowspan="3" style="background:#DCDCDC;" align="center" + |'''TIRADS 4'''
|Prominent cribriform pattern with solid and spindle cell areas as well as squamous morules. This variant is often associated with familial adenomatous polyposis.
! style="background:#DCDCDC;" align="center" + |4a
|
| style="background:#F5F5F5;" + |One suspicious feature
| rowspan="3" style="background:#F5F5F5;" + |
* Suspicious lesions:
** Solid component
** High stiffness of [[nodule]] on elastography if available
** Markedly hypoechoic [[nodule]]
** Microlobulations or irregular margins
** [[Microcalcification|Microcalcifications]]
** Taller-than-wider shape
| style="background:#F5F5F5;" + |5-10% risk of malignancy
|-
|-
|hobnail variant
! style="background:#DCDCDC;" align="center" + |4b
|harbors ''BRAF'' V600E mutations and appears to be associated with a high risk of distant metastases and an increased disease-specific mortality
| style="background:#F5F5F5;" + |Two suspicious features
|
| rowspan="2" style="background:#F5F5F5;" + |10-80% risk of malignancy
|}
 
==== Thyroid nodule classification based on the sonographhic features: ====
Classification system has been proposed by Horvath et al 3, with a modified recommendation from Jin Kwak et al 4.
{| class="wikitable"
! colspan="2" |
!
!
!
|-
|-
| colspan="2" |'''TIRADS 1'''
! style="background:#DCDCDC;" align="center" + |4c
|Normal thyroid gland
| style="background:#F5F5F5;" + |Three/four suspicious features
|
|
|-
|-
| colspan="2" |'''TIRADS 2'''
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 5'''
|Benign lesions
| style="background:#F5F5F5;" + |All five suspicious features
|
| style="background:#F5F5F5;" + |Probably [[malignant]] lesions (more than 80% risk of [[malignancy]])
* Avascular anechoic lesion with echogenic specks (colloid type I)
| style="background:#F5F5F5;" + |>80% risk of [[malignancy]]
* vascular heteroechoic non-expansile, non-encapsulated nodules with peripheral halo (colloid type II)
* isoechoic or heteroechoic, non-encapsulated, expansile vascular nodules (colloid type III)
|0% risk of malignancy
|-
|-
| colspan="2" |'''TIRADS 3'''
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 6'''
|Probably benign lesions
| colspan="3" style="background:#F5F5F5;" + |Biopsy proven [[malignancy]]
|
|}
* Nodule property:
 
** Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity, usually in setting of Hashimoto's thyroiditis (Hashimoto's pseudonodule)
== Classification Of Neoplastic Thyroid Nodules Based On Their Origin: ==
|<5% risk of malignancy
{|
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Prevalence
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Histologic Classification
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Subclass
|-
|-
| rowspan="3" |'''TIRADS 4'''
! rowspan="4" style="background:#DCDCDC;" align="center" + |[[Thyroid cancer|Nonmedullary thyroid cancers (NMTCs)]]
|4a
| rowspan="4" style="background:#F5F5F5;" align="center" + |95% of [[Tumor|tumors]]
|One suspicious feature
| rowspan="4" style="background:#F5F5F5;" align="center" + |[[Thyroid]] [[epithelial cells]]
| rowspan="3" |
| style="background:#F5F5F5;" align="center" + |[[Papillary thyroid cancer|Papillary]] (85%)
* Suspicious lesions:
| style="background:#F5F5F5;" + |
** solid component
* Classic variant
*** high stiffness of nodule on elastography if available
* Tall cell variant
** markedly hypoechoic nodule
* Insular variant
** microlobulations or irregular margins
* Columnar variant
** microcalcifications
* [[Hurthle cells|Hürthle]] or [[Oxyphilic adenoma|oxyphilic]] variant
** taller-than-wider shape
* Solid or trabecular variant
|5-10% risk of malignancy
* Clear cell variant
* Diffuse sclerosing variant
* Cribriform-morular variant
* Hobnail variant
|-
|-
|4b
| style="background:#F5F5F5;" align="center" + |[[Follicular thyroid cancer|Follicular]] (11%)
|Two suspicious features
| style="background:#F5F5F5;" + |
| rowspan="2" |10-80% risk of malignancy
* [[Benign]] follicular adenoma
* Minimally invasive follicular [[carcinoma]]
* Widely invasive follicular [[carcinoma]]
* Encapsulated follicular variant of [[papillary thyroid cancer]]
* Infiltrative variant of [[papillary thyroid cancer]]
|-
|-
|4c
| colspan="2" style="background:#F5F5F5;" + | [[Hurthle cells|Hürthle cell]] (3%)
|Three/four suspicious features
|-
|-
| colspan="2" |'''TIRADS 5'''
| colspan="2" style="background:#F5F5F5;" + | [[Anaplastic thyroid cancer|Anaplastic]] (1%)
|All five suspicious features
|Probably malignant lesions (more than 80% risk of malignancy)
|>80% risk of malignancy
|-
|-
| colspan="2" |'''TIRADS 6'''
! style="background:#DCDCDC;" align="center" + |[[Medullary thyroid cancer|Medullary thyroid cancers (MTCs)]]
|Biopsy proven malignancy
| style="background:#F5F5F5;" align="center" + |5% of all [[thyroid]] [[malignancies]]
|
| colspan="2" style="background:#F5F5F5;" align="center" + | [[Parafollicular cells|Calcitonin-producing parafollicular cells]]
|
| style="background:#F5F5F5;" + |
*20% they are familial and occur as part of the [[multiple endocrine neoplasia]] (MEN) syndromes
|}
|}



Latest revision as of 15:32, 3 November 2017

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahshid Mir, M.D. [2]

Overview

There are various methods for classifying a thyroid nodule. A method has been developed by the National Cancer Institute (NCI) to address terminology and other issues related to thyroid fine-needle aspiration (FNA), called "The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)". The other classification method is the TNM classification (tumor-node-metastasis) method developed by the American Joint Committee on Cancer and the International Union against Cancer focused on prognosis has been established to avoid heterogeneity of prognostic classification schemes used for differentiated thyroid cancers. Thyroid nodules may also be classified based on their ultrasound properties according to the TIRAD classification method, which has been proposed by Horvath et al, with a modified recommendation from Jin Kwak et al, and finally, thyroid nodules may also be classified on the basis of origin.

Classification

 
 
 
 
 
 
 
Thyroid nodule classification
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Bethesda classification system
 
 
 
 
 
 
 
 
 
 
TIRAD classification system
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Based on thyroid cytopathology
 
 
 
 
 
 
 
 
 
 
Based on sonographic features
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Benign
•Nondiagnostic or Unsatisfactory
•Follicular lesion of undetermined significance
Atypia of undetermined significance
•Follicular neoplasm
•Suspicious for a follicular neoplasm
Malignant
 
 
 
 
 
 
 
 
 
 
•TIRADS 1=Normal thyroid gland
•TIRADS 2=Benign lesions
•TIRADS 3=Probably benign lesions
•TIRADS 4= Contain 1-4 suspicious features
•TIRADS 5=Contain all five suspicious features
•TIRADS 6=Biopsy proven malignancy
 
 
 
 
 
 
 
Differentiated and anaplastic thyroid carcinoma
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TNM staging AJCC UICC 2017
 
 
 
 
 
Classification based on their origin
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
•Primary tumor (T)
•Regional lymph nodes (N)
•Distant metastasis (M)
 
 
Nonmedullary (epithelial) thyroid cancers (NMTCs)
•Papillary cell tumors
•Follicular tumors
•Hurthle cell tumors
•Anaplastic tumors
 
 
 
Medullary thyroid cancers
 
 

The Bethesda System For Reporting Thyroid Cytopathology

To address terminology and other issues related to thyroid fine-needle aspiration (FNA), the National Cancer Institute (NCI) developed a new classification method called "The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)".[1]

Classification FNA cytology Predicted risk of malignancy
Benign 0–3 %
Nondiagnostic or unsatisfactory --- 1–4 %
Follicular lesion of undetermined significance
  • Mixed macro- and microfollicular nodules
5–15 %
Atypia of undetermined significance
Follicular neoplasm 15–30 %
Suspicious for a follicular neoplasm 60–75 %
Malignant 97–99 %

Abbreviations: PTC- Papillary thyroid carcinoma, MTC- Medullary thyroid carcinoma

Classification Based On TNM Staging

The TNM classification (tumor-node-metastasis) was adopted by the American Joint Committee on Cancer and the International Union against Cancer more than 10 years ago. This classification system mainly focuses on prognosis and is developed to avoid heterogeneity of prognostic classification schemes used for differentiated thyroid cancers.[2]

Differentiated and anaplastic thyroid carcinoma TNM staging AJCC UICC 2017

Papillary, follicular, poorly differentiated, Hurthle cell and anaplastic thyroid carcinoma
Primary tumor (T) Regional lymph nodes (N) Distant metastasis (M)
T category T criteria N category N criteria M category M criteria
TX Primary tumor cannot be assessed NX Regional lymph nodes cannot be assessed M0 No distant metastasis
T0 No evidence of primary tumor N0 No evidence of locoregional lymph node metastasis M1 Distant metastasis
T1 Tumor ≤2 cm in greatest dimension limited to the thyroid N0a One or more cytologically or histologically confirmed benign lymph nodes
T1a Tumor ≤1 cm in greatest dimension limited to the thyroid N0b No radiological or clinical evidence of local regional lymph node metastases
T1b Tumor >1 cm but ≤2 cm in greatest dimension limited to the thyroid N1 Metastasis to regional nodes
T2 Tumor >2 cm but ≤4 cm in greatest dimension limited to the thyroid N1a Metastases to level VI or VII (pretracheal, paratracheal, or prelaryngeal/Delphian, or upper mediastinal) lymph nodes. This can be unilateral or bilateral disease
T3 Tumor >4 cm limited to the thyroid, or gross extrathyroidal extension invading only strap muscles N1b Metastasis to unilateral, bilateral, or contralateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes
T3a Tumor >4 cm limited to the thyroid
T3b Gross extrathyroidal extension invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid, or omohyoid muscles) from a tumor of any size
T4 Includes gross extrathyroidal extension
T4a Gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve from a tumor of any size
T4b Gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels from a tumor of any size

Thyroid Nodule Classification Based On Ultrasound Features

A classification system has been proposed by Horvath et al, with a modified recommendation from Jin Kwak et al.[3]

Ultrasound classification Features Risk of Malignancy
TIRADS 1 Normal thyroid gland
TIRADS 2 Benign lesions
  • Avascular anechoic lesion with echogenic specks (colloid type I)
  • Vascular heteroechoic non-expansile, non-encapsulated nodules with peripheral halo (colloid type II)
  • Isoechoic or heteroechoic, non-encapsulated, expansile vascular nodules (colloid type III)
0% risk of malignancy
TIRADS 3 Probably benign lesions <5% risk of malignancy
TIRADS 4 4a One suspicious feature
  • Suspicious lesions:
    • Solid component
    • High stiffness of nodule on elastography if available
    • Markedly hypoechoic nodule
    • Microlobulations or irregular margins
    • Microcalcifications
    • Taller-than-wider shape
5-10% risk of malignancy
4b Two suspicious features 10-80% risk of malignancy
4c Three/four suspicious features
TIRADS 5 All five suspicious features Probably malignant lesions (more than 80% risk of malignancy) >80% risk of malignancy
TIRADS 6 Biopsy proven malignancy

Classification Of Neoplastic Thyroid Nodules Based On Their Origin:

Origin Prevalence Origin Histologic Classification Subclass
Nonmedullary thyroid cancers (NMTCs) 95% of tumors Thyroid epithelial cells Papillary (85%)
  • Classic variant
  • Tall cell variant
  • Insular variant
  • Columnar variant
  • Hürthle or oxyphilic variant
  • Solid or trabecular variant
  • Clear cell variant
  • Diffuse sclerosing variant
  • Cribriform-morular variant
  • Hobnail variant
Follicular (11%)
Hürthle cell (3%)
Anaplastic (1%)
Medullary thyroid cancers (MTCs) 5% of all thyroid malignancies Calcitonin-producing parafollicular cells

References

  1. Cibas ES, Ali SZ (2009). "The Bethesda System for Reporting Thyroid Cytopathology". Thyroid. 19 (11): 1159–65. doi:10.1089/thy.2009.0274. PMID 19888858.
  2. Loh KC, Greenspan FS, Gee L, Miller TR, Yeo PP (1997). "Pathological tumor-node-metastasis (pTNM) staging for papillary and follicular thyroid carcinomas: a retrospective analysis of 700 patients". J. Clin. Endocrinol. Metab. 82 (11): 3553–62. doi:10.1210/jcem.82.11.4373. PMID 9360506.
  3. Horvath E, Majlis S, Rossi R, Franco C, Niedmann JP, Castro A, Dominguez M (2009). "An ultrasonogram reporting system for thyroid nodules stratifying cancer risk for clinical management". J. Clin. Endocrinol. Metab. 94 (5): 1748–51. doi:10.1210/jc.2008-1724. PMID 19276237.

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