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== Overview ==
== Overview ==
There are different methods regarding thyroid nodule classification. 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]] and is adopted to avoid heterogeneity of prognostic classification schemes used for differentiated [[Thyroid cancer|thyroid cancers]]. Thyroid nodules may also get classified based on their [[ultrasound]] properties regarding TIRAD classification method which has been proposed by Horvath et al, with a modified recommendation from Jin Kwak et al, and finally may get classified based on their origin.
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/end}}
{{familytree/end}}


== The Bethesda System for Reporting Thyroid Cytopathology ==
== 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>
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>
{|
{|
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| style="background:#F5F5F5;" align="center" + |0–3 %
| style="background:#F5F5F5;" align="center" + |0–3 %
|-
|-
! style="background:#DCDCDC;" align="center" + |Nondiagnostic or Unsatisfactory
! style="background:#DCDCDC;" align="center" + |Nondiagnostic or unsatisfactory
| style="background:#F5F5F5;" align="center" + | ---
| style="background:#F5F5F5;" align="center" + | ---
| style="background:#F5F5F5;" align="center" + |1–4 %
| style="background:#F5F5F5;" align="center" + |1–4 %
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| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
* Microfollicular nodules
* Microfollicular nodules
** [[Hurthle cell carcinoma|Hurthle cell lesions]]
* [[Hurthle cell carcinoma|Hurthle cell lesions]]
| style="background:#F5F5F5;" align="center" + |15–30 %
| style="background:#F5F5F5;" align="center" + |15–30 %
|-
|-
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| style="background:#F5F5F5;" align="center" + |97–99 %
| style="background:#F5F5F5;" align="center" + |97–99 %
|}
|}
'''Abbreviations''': '''PTC'''- ''[[Papillary thyroid carcinoma]]'', '''MTC'''- ''[[Medullary thyroid cancer|Medullary thyroid carcinoma]]''


==Classification based on TNM==
==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>
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>


==== Differentiated and anaplastic thyroid carcinoma TNM staging AJCC UICC 2017 ====
==== Differentiated and anaplastic thyroid carcinoma TNM staging AJCC UICC 2017 ====
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|-
|-
! style="background:#DCDCDC;" align="center" + |TX
! style="background:#DCDCDC;" align="center" + |TX
| colspan="4" style="background:#F5F5F5;" + |Primary tumor cannot be assessed
| colspan="4" style="background:#F5F5F5;" + |Primary [[tumor]] cannot be assessed
! style="background:#DCDCDC;" align="center" + |NX
! style="background:#DCDCDC;" align="center" + |NX
| style="background:#F5F5F5;" + |Regional [[Lymph node|lymph nodes]] cannot be assessed
| style="background:#F5F5F5;" + |Regional [[Lymph node|lymph nodes]] cannot be assessed
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|-
|-
! style="background:#DCDCDC;" align="center" + |T0
! style="background:#DCDCDC;" align="center" + |T0
| colspan="4" style="background:#F5F5F5;" + |No evidence of primary tumor
| colspan="4" style="background:#F5F5F5;" + |No evidence of primary [[tumor]]
! style="background:#DCDCDC;" align="center" + |N0
! style="background:#DCDCDC;" align="center" + |N0
| style="background:#F5F5F5;" + |No evidence of locoregional [[lymph node]] [[metastasis]]
| style="background:#F5F5F5;" + |No evidence of locoregional [[lymph node]] [[metastasis]]
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| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤2 cm in greatest dimension limited to the [[thyroid]]
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤2 cm in greatest dimension limited to the [[thyroid]]
! style="background:#DCDCDC;" align="center" + |N0a
! style="background:#DCDCDC;" align="center" + |N0a
| style="background:#F5F5F5;" + |One or more cytologically or histologically confirmed benign [[lymph nodes]]
| style="background:#F5F5F5;" + |One or more cytologically or [[histologically]] confirmed [[benign]] [[lymph nodes]]
| colspan="2" rowspan="5" style="background:#F5F5F5;" + |
| colspan="2" rowspan="5" style="background:#F5F5F5;" + |
|-
|-
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| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤1 cm in greatest dimension limited to the [[thyroid]]
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] ≤1 cm in greatest dimension limited to the [[thyroid]]
! style="background:#DCDCDC;" align="center" + |N0b
! style="background:#DCDCDC;" align="center" + |N0b
| style="background:#F5F5F5;" + |No radiological or clinical evidence of locoregional [[lymph node metastases]]
| style="background:#F5F5F5;" + |No [[radiological]] or clinical evidence of local regional [[lymph node metastases]]
|-
|-
! style="background:#DCDCDC;" align="center" + |T1b
! style="background:#DCDCDC;" align="center" + |T1b
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >1 cm but ≤2 cm in greatest dimension limited to the [[thyroid]]
| 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:#DCDCDC;" align="center" + |N1
| style="background:#F5F5F5;" + |[[Metastasis]] to regional nodes
| style="background:#F5F5F5;" + |[[Metastasis]] to regional [[Lymph nodes|nodes]]
|-
|-
! style="background:#DCDCDC;" align="center" + |T2
! style="background:#DCDCDC;" align="center" + |T2
| colspan="4" style="background:#F5F5F5;" + |[[Tumor]] >2 cm but ≤4 cm in greatest dimension limited to the [[thyroid]]
| 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:#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
| 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
|-
|-
! style="background:#DCDCDC;" align="center" + |T3
! 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
| 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:#DCDCDC;" align="center" + |N1b
| style="background:#F5F5F5;" + |[[Metastasis]] to unilateral, bilateral, or contralateral lateral neck [[lymph nodes]] (levels I, II, III, IV, or V) or [[retropharyngeal lymph nodes]]
| style="background:#F5F5F5;" + |[[Metastasis]] to unilateral, bilateral, or [[contralateral]] [[neck]] [[lymph nodes]] (levels I, II, III, IV, or V) or [[retropharyngeal lymph nodes]]
|-
|-
! style="background:#DCDCDC;" align="center" + |T3a
! style="background:#DCDCDC;" align="center" + |T3a
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|-
|-
! style="background:#DCDCDC;" align="center" + |T3b
! style="background:#DCDCDC;" align="center" + |T3b
| colspan="4" style="background:#F5F5F5;" + |Gross extrathyroidal extension invading only strap muscles ([[sternohyoid]], [[sternothyroid]], [[thyrohyoid]], or [[Omohyoid muscle|omohyoid muscles]]) from a [[tumor]] of any size
| 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
|-
|-
! style="background:#DCDCDC;" align="center" + |T4
! style="background:#DCDCDC;" align="center" + |T4
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|-
|-
! style="background:#DCDCDC;" align="center" + |T4b
! style="background:#DCDCDC;" align="center" + |T4b
| colspan="4" style="background:#F5F5F5;" + |Gross extrathyroidal extension invading [[prevertebral fascia]] or encasing the [[carotid artery]] or [[mediastinal]] vessels from a [[tumor]] of any size
| 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 the Ultrasound Features ==
== Thyroid Nodule Classification Based On Ultrasound 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>
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" + |Ultrasound classification
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| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
* [[Avascular]] anechoic lesion with [[echogenic]] specks (colloid type I)
* [[Avascular]] anechoic lesion with [[echogenic]] specks (colloid type I)
* Vascular heteroechoic non-expansile, non-encapsulated [[nodules]] with peripheral halo (colloid type II)
* [[Vascular]] heteroechoic non-expansile, non-encapsulated [[nodules]] with peripheral halo (colloid type II)
* Isoechoic or heteroechoic, non-encapsulated, expansile vascular nodules (colloid type III)
* Isoechoic or heteroechoic, non-encapsulated, expansile [[vascular]] nodules (colloid type III)
| style="background:#F5F5F5;" + |0% risk of malignancy
| style="background:#F5F5F5;" + |0% risk of malignancy
|-
|-
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| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
* [[Nodule]] property:
* [[Nodule]] property:
** Hyperechoic, iso-echoic or hypoechoic nodules, with partially formed capsule and peripheral vascularity, usually in the setting of [[Hashimoto's thyroiditis]]
** 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
| style="background:#F5F5F5;" + |<5% risk of malignancy
|-
|-
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* Suspicious lesions:
* Suspicious lesions:
** Solid component
** Solid component
*** High stiffness of [[nodule]] on elastography if available
** High stiffness of [[nodule]] on elastography if available
** Markedly hypoechoic [[nodule]]
** Markedly hypoechoic [[nodule]]
** Microlobulations or irregular margins
** Microlobulations or irregular margins
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! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 5'''
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 5'''
| style="background:#F5F5F5;" + |All five suspicious features
| style="background:#F5F5F5;" + |All five suspicious features
| style="background:#F5F5F5;" + |Probably malignant lesions (more than 80% risk of [[malignancy]])
| style="background:#F5F5F5;" + |Probably [[malignant]] lesions (more than 80% risk of [[malignancy]])
| style="background:#F5F5F5;" + |>80% risk of malignancy
| style="background:#F5F5F5;" + |>80% risk of [[malignancy]]
|-
|-
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 6'''
! colspan="2" style="background:#DCDCDC;" align="center" + |'''TIRADS 6'''
Line 204: Line 205:
|}
|}


== Classification of neoplastic thyroid nodules based on their origin: ==
== Classification Of Neoplastic Thyroid Nodules Based On Their Origin: ==
{|
{|
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
! style="background:#4479BA; color: #FFFFFF;" align="center" + |Origin
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|-
|-
! rowspan="4" style="background:#DCDCDC;" align="center" + |[[Thyroid cancer|Nonmedullary thyroid cancers (NMTCs)]]
! rowspan="4" style="background:#DCDCDC;" align="center" + |[[Thyroid cancer|Nonmedullary thyroid cancers (NMTCs)]]
| rowspan="4" style="background:#F5F5F5;" align="center" + |95% of tumors  
| rowspan="4" style="background:#F5F5F5;" align="center" + |95% of [[Tumor|tumors]]
| rowspan="4" style="background:#F5F5F5;" align="center" + |Thyroid epithelial cells
| rowspan="4" style="background:#F5F5F5;" align="center" + |[[Thyroid]] [[epithelial cells]]
| style="background:#F5F5F5;" align="center" + |[[Papillary thyroid cancer|Papillary]] (85%)
| style="background:#F5F5F5;" align="center" + |[[Papillary thyroid cancer|Papillary]] (85%)
| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
Line 221: Line 222:
* Insular variant  
* Insular variant  
* Columnar variant  
* Columnar variant  
* Hürthle or oxyphilic variant
* [[Hurthle cells|Hürthle]] or [[Oxyphilic adenoma|oxyphilic]] variant
* Solid or trabecular variant  
* Solid or trabecular variant  
* Clear cell variant  
* Clear cell variant  
Line 230: Line 231:
| style="background:#F5F5F5;" align="center" + |[[Follicular thyroid cancer|Follicular]] (11%)
| style="background:#F5F5F5;" align="center" + |[[Follicular thyroid cancer|Follicular]] (11%)
| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
* Benign follicular adenoma
* [[Benign]] follicular adenoma
* Minimally invasive follicular carcinoma
* Minimally invasive follicular [[carcinoma]]
* Widely invasive follicular carcinoma
* Widely invasive follicular [[carcinoma]]
* Encapsulated follicular variant of papillary thyroid cancer
* Encapsulated follicular variant of [[papillary thyroid cancer]]
* Infiltrative variant of papillary thyroid cancer
* Infiltrative variant of [[papillary thyroid cancer]]
|-
|-
| colspan="2" style="background:#F5F5F5;" + | Hürthle cell (3%)
| colspan="2" style="background:#F5F5F5;" + | [[Hurthle cells|Hürthle cell]] (3%)
|-
|-
| colspan="2" style="background:#F5F5F5;" + | [[Anaplastic thyroid cancer|Anaplastic]] (1%)
| colspan="2" style="background:#F5F5F5;" + | [[Anaplastic thyroid cancer|Anaplastic]] (1%)
|-
|-
! style="background:#DCDCDC;" align="center" + |[[Medullary thyroid cancer|Medullary thyroid cancers (MTCs)]]  
! style="background:#DCDCDC;" align="center" + |[[Medullary thyroid cancer|Medullary thyroid cancers (MTCs)]]  
| style="background:#F5F5F5;" align="center" + |5% of all thyroid malignancies
| style="background:#F5F5F5;" align="center" + |5% of all [[thyroid]] [[malignancies]]
| colspan="2" style="background:#F5F5F5;" align="center" + | [[Parafollicular cells|Calcitonin-producing parafollicular cells]]  
| colspan="2" style="background:#F5F5F5;" align="center" + | [[Parafollicular cells|Calcitonin-producing parafollicular cells]]  
| style="background:#F5F5F5;" + |
| style="background:#F5F5F5;" + |
*20% they are familial and occur as part of the multiple endocrine neoplasia (MEN) syndromes
*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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