Thyroid nodule classification: Difference between revisions

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== Overview ==
== Overview ==
 
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 ==


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{{familytree | | | | | | | | B01 | | | | |B01=Thyroid nodule classification}}
{{familytree | | | | | | | | B01 | | | | |B01=Thyroid nodule classification}}
{{familytree | | |,|-|-|-|-|-|+|-|-|-|-|-|.| }}
{{familytree | | |,|-|-|-|-|-|+|-|-|-|-|-|.| }}
{{familytree | | C01 | | | | C02 | | | | C03 |C01= '''Bethesda classification system''' |C02= '''TNM staging AJCC UICC 2017''' |C03= '''TIRAD classification system'''}}
{{familytree | | C01 | | | | |!| | | | | C03 |C01= '''Bethesda classification system''' |C03= '''TIRAD classification system'''}}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | | C01 | | | | C02 | | | | C03 |C01= Based on thyroid cytopathology |C02= For differentiated and anaplastic thyroid carcinoma |C03= Based on sonographhic features}}
{{familytree | | C01 | | | | |!| | | | | C03 |C01= Based on thyroid [[cytopathology]] |C03= Based on [[Ultrasound|sonographic]] features}}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | | |!| | | | | |!| | | | | |!| }}
{{familytree | boxstyle=text-align: left; | | C01 | | | | C02 | | | | 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> |C02= Papillary, follicular, poorly differentiated, Hurthle cell and anaplastic thyroid carcinoma: <br> •Primary tumor (T) <br> •Regional lymph nodes (N) <br> •Distant metastasis (M) |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 | 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}}
{{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>
==== 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>
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Classification
{| class="wikitable"
! style="background:#4479BA; color: #FFFFFF;" align="center" + |FNA cytology
!classification
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Predicted risk of malignancy
!FNA cytology
!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 ====
!Subclass
{|
|-
! colspan="9" style="background:#4479BA; color: #FFFFFF;" align="center" + |Papillary, follicular, poorly differentiated, Hurthle cell and anaplastic thyroid carcinoma
|-
! 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)
! colspan="2" style="background:#4479BA; color: #FFFFFF;" align="center" + |Distant metastasis (M)
|-
|-
| rowspan="4" |Nonmedullary thyroid cancers (NMTCs)
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''T category'''
| rowspan="4" |95% of tumors
! colspan="4" style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''T criteria'''
| rowspan="4" |thyroid epithelial cells
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''N category'''
|papillary (85%)
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''N criteria'''
|95% are sporadic tumors
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''M category'''
5% may be related to inherited genetics due to familial origin
! style="background:#7d7d7d; color: #FFFFFF;" align="center" + |'''M criteria'''
* 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%)
! style="background:#DCDCDC;" align="center" + |TX
|
| colspan="4" style="background:#F5F5F5;" + |Primary [[tumor]] cannot be assessed
* Benign follicular adenoma
! style="background:#DCDCDC;" align="center" + |NX
* Minimally invasive follicular carcinoma
| style="background:#F5F5F5;" + |Regional [[Lymph node|lymph nodes]] cannot be assessed
* Widely invasive follicular carcinoma
! style="background:#DCDCDC;" align="center" + |M0
* Encapsulated follicular variant of papillary thyroid cancer
| style="background:#F5F5F5;" + |No distant [[metastasis]]
* Infiltrative variant of papillary thyroid cancer
|-
|-
|Hürthle cell (3%)
! style="background:#DCDCDC;" align="center" + |T0
|
| colspan="4" style="background:#F5F5F5;" + |No evidence of primary [[tumor]]
! style="background:#DCDCDC;" align="center" + |N0
| style="background:#F5F5F5;" + |No evidence of locoregional [[lymph node]] [[metastasis]]
! style="background:#DCDCDC;" align="center" + |M1
| style="background:#F5F5F5;" + |Distant [[metastasis]]
|-
|-
|anaplastic (1%)
! style="background:#DCDCDC;" align="center" + |T1
|
| 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;" + |
|-
|-
|Medullary thyroid cancers (MTCs)
! style="background:#DCDCDC;" align="center" + |T1a
|5% of all thyroid malignancies
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤1 cm in greatest dimension limited to the [[thyroid]]
|calcitonin-producing parafollicular cells
! style="background:#DCDCDC;" align="center" + |N0b
|
| style="background:#F5F5F5;" + |No [[radiological]] or clinical evidence of local regional [[lymph node metastases]]
|20% they are familial and occur as part of the multiple endocrine neoplasia (MEN) syndromes
|}
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
 
==== Thyroid nodule classification based on the sonographhic features: ====
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>
{| class="wikitable"
! colspan="2" |
!
!
!
|-
|-
| colspan="2" |'''TIRADS 1'''
! style="background:#DCDCDC;" align="center" + |T1b
|Normal thyroid gland
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >1 cm but ≤2 cm in greatest dimension limited to the [[thyroid]]
|
! style="background:#DCDCDC;" align="center" + |N1
|
| style="background:#F5F5F5;" + |[[Metastasis]] to regional [[Lymph nodes|nodes]]
|-
|-
| colspan="2" |'''TIRADS 2'''
! style="background:#DCDCDC;" align="center" + |T2
|Benign lesions
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >2 cm but ≤4 cm in greatest dimension limited to the [[thyroid]]
|
! style="background:#DCDCDC;" align="center" + |N1a
* Avascular anechoic lesion with echogenic specks (colloid type I)
| 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
* 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'''
! style="background:#DCDCDC;" align="center" + |T3
|Probably benign lesions
| 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
* Nodule property:
| style="background:#F5F5F5;" + |[[Metastasis]] to unilateral, bilateral, or [[contralateral]] [[neck]] [[lymph nodes]] (levels I, II, III, IV, or V) or [[retropharyngeal lymph nodes]]
** Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity, usually in setting of Hashimoto's thyroiditis (Hashimoto's pseudonodule)
|<5% risk of malignancy
|-
|-
| rowspan="3" |'''TIRADS 4'''
! style="background:#DCDCDC;" align="center" + |T3a
|4a
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >4 cm limited to the [[thyroid]]
|One suspicious feature
| colspan="4" rowspan="5" style="background:#F5F5F5;" + |
| rowspan="3" |
* 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
! style="background:#DCDCDC;" align="center" + |T3b
|Two suspicious features
| 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
| rowspan="2" |10-80% risk of malignancy
|-
|-
|4c
! style="background:#DCDCDC;" align="center" + |T4
|Three/four suspicious features
| colspan="4" style="background:#F5F5F5;" + |Includes gross extrathyroidal extension
|-
|-
| colspan="2" |'''TIRADS 5'''
! style="background:#DCDCDC;" align="center" + |T4a
|All five suspicious features
| 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
|Probably malignant lesions (more than 80% risk of malignancy)
|>80% risk of malignancy
|-
|-
| colspan="2" |'''TIRADS 6'''
! style="background:#DCDCDC;" align="center" + |T4b
|Biopsy proven malignancy
| 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
|
|
|}
|}


==Classification based on TNM==
== Thyroid Nodule Classification Based On Ultrasound Features ==
Differentiated and anaplastic thyroid carcinoma TNM staging AJCC UICC 2017
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>
{| class="wikitable"
{|
! 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
|-
|-
| colspan="9" |Papillary, follicular, poorly differentiated, Hurthle cell and anaplastic thyroid carcinoma
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 1'''
| colspan="2" style="background:#F5F5F5;" + |Normal [[thyroid gland]]
| style="background:#F5F5F5;" + |
|-
|-
| colspan="5" |Primary tumor (T)
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 2'''
| colspan="2" |Regional lymph nodes (N)
| style="background:#F5F5F5;" + |[[Benign]] lesions
| colspan="2" |Distant metastasis (M)
| 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
|-
|-
|'''T category'''
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 3'''
| colspan="4" |'''T criteria'''
| style="background:#F5F5F5;" + |Probably [[Benign|benign lesions]]
|'''N category'''
| style="background:#F5F5F5;" + |
|'''N criteria'''
* [[Nodule]] property:
|'''M category'''
** Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral [[vascularity]], usually in the setting of [[Hashimoto's thyroiditis]]
|'''M criteria'''
| style="background:#F5F5F5;" + |<5% risk of malignancy
|-
|-
|TX
! rowspan="3" style="background:#DCDCDC;" align="center" + |'''TIRADS 4'''
| colspan="4" |Primary tumor cannot be assessed
! style="background:#DCDCDC;" align="center" + |4a
|NX
| style="background:#F5F5F5;" + |One suspicious feature
|Regional lymph nodes cannot be assessed
| rowspan="3" style="background:#F5F5F5;" + |
|M0
* Suspicious lesions:
|No distant metastasis
** 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
|-
|-
|T0
! style="background:#DCDCDC;" align="center" + |4b
| colspan="4" |No evidence of primary tumor
| style="background:#F5F5F5;" + |Two suspicious features
|N0
| rowspan="2" style="background:#F5F5F5;" + |10-80% risk of malignancy
|No evidence of locoregional lymph node metastasis
|M1
|Distant metastasis
|-
|-
|T1
! style="background:#DCDCDC;" align="center" + |4c
| colspan="4" |Tumor ≤2 cm in greatest dimension limited to the thyroid
| style="background:#F5F5F5;" + |Three/four suspicious features
|N0a
|One or more cytologically or histologically confirmed benign lymph nodes
|
|
|-
|-
|T1a
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 5'''
| colspan="4" |Tumor ≤1 cm in greatest dimension limited to the thyroid
| style="background:#F5F5F5;" + |All five suspicious features
|N0b
| style="background:#F5F5F5;" + |Probably [[malignant]] lesions (more than 80% risk of [[malignancy]])
|No radiologic or clinical evidence of locoregional lymph node metastasis
| style="background:#F5F5F5;" + |>80% risk of [[malignancy]]
|
|
|-
|-
|T1b
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 6'''
| colspan="4" |Tumor >1 cm but ≤2 cm in greatest dimension limited to the thyroid
| colspan="3" style="background:#F5F5F5;" + |Biopsy proven [[malignancy]]
|N1
|}
|Metastasis to regional nodes
 
|
== Classification Of Neoplastic Thyroid Nodules Based On Their Origin: ==
|
{|
|-
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
|T2
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Prevalence
| colspan="4" |Tumor >2 cm but ≤4 cm in greatest dimension limited to the thyroid
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
|N1a
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Histologic Classification
|Metastasis to level VI or VII (pretracheal, paratracheal, or prelaryngeal/Delphian, or upper mediastinal) lymph nodes. This can be unilateral or bilateral disease.
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Subclass
|
|
|-
|T3
| colspan="4" |Tumor >4 cm limited to the thyroid, or gross extrathyroidal extension invading only strap muscles
|N1b
|Metastasis to unilateral, bilateral, or contralateral lateral neck lymph nodes (levels I, II, III, IV, or V) or retropharyngeal lymph nodes
|
|
|-
|-
|T3a
! rowspan="4" style="background:#DCDCDC;" align="center" + |[[Thyroid cancer|Nonmedullary thyroid cancers (NMTCs)]]
| colspan="4" |Tumor >4 cm limited to the thyroid
| rowspan="4" style="background:#F5F5F5;" align="center" + |95% of [[Tumor|tumors]]
|
| rowspan="4" style="background:#F5F5F5;" align="center" + |[[Thyroid]] [[epithelial cells]]
|
| style="background:#F5F5F5;" align="center" + |[[Papillary thyroid cancer|Papillary]] (85%)
|
| style="background:#F5F5F5;" + |
|
* Classic variant
* Tall cell variant
* Insular variant
* Columnar variant
* [[Hurthle cells|Hürthle]] or [[Oxyphilic adenoma|oxyphilic]] variant
* Solid or trabecular variant
* Clear cell variant
* Diffuse sclerosing variant
* Cribriform-morular variant
* Hobnail variant
|-
|-
|T3b
| style="background:#F5F5F5;" align="center" + |[[Follicular thyroid cancer|Follicular]] (11%)
| colspan="4" |Gross extrathyroidal extension invading only strap muscles (sternohyoid, sternothyroid, thyrohyoid, or omohyoid muscles) from a tumor of any size
| style="background:#F5F5F5;" + |
|
* [[Benign]] follicular adenoma
|
* Minimally invasive follicular [[carcinoma]]
|
* Widely invasive follicular [[carcinoma]]
|
* Encapsulated follicular variant of [[papillary thyroid cancer]]
* Infiltrative variant of [[papillary thyroid cancer]]
|-
|-
|T4
| colspan="2" style="background:#F5F5F5;" + | [[Hurthle cells|Hürthle cell]] (3%)
| colspan="4" |Includes gross extrathyroidal extension
|
|
|
|
|-
|-
|T4a
| colspan="2" style="background:#F5F5F5;" + | [[Anaplastic thyroid cancer|Anaplastic]] (1%)
| colspan="4" |Gross extrathyroidal extension invading subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve from a tumor of any size
|
|
|
|
|-
|-
|T4b
! style="background:#DCDCDC;" align="center" + |[[Medullary thyroid cancer|Medullary thyroid cancers (MTCs)]]
| colspan="4" |Gross extrathyroidal extension invading prevertebral fascia or encasing the carotid artery or mediastinal vessels from a tumor of any size
| 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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