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Update to the College of American Pathologists reporting on thyroid carcinomas.

Ghossein R - Head Neck Pathol (2009)

Bottom Line: While there are defined criteria for invasion, there is not universal agreement in what constitutes capsular invasion, angioinvasion and extrathyroidal invasion.These findings assist clinicians in their assessment of the recurrence risk and potential for metastatic disease.Large meticulous clinico-pathologic and molecular studies with long term follow up are still needed in order to increase the impact of microscopic examination on the prognosis and management of TC.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, 10065, New York, NY, USA. ghosseir@mskcc.org

ABSTRACT

Background: The reporting of thyroid carcinomas follows the recommendations of the College of American Pathologists (CAP) protocols and includes papillary carcinoma, follicular carcinoma, anaplastic carcinoma and medullary carcinoma. Despite past and recent efforts, there are a number of controversial issues in the classification and diagnosis of thyroid carcinomas (TC) that, potentially impact on therapy and prognosis of patients with TC.

Discussion: The most updated version of the CAP thyroid cancer protocol incorporates recent changes in histologic classification as well as changes in the staging of thyroid cancers as per the updated American Joint Commission on Cancer staging manual. Among the more contentious issues in the pathology of thyroid carcinoma include the defining criteria for tumor invasiveness. While there are defined criteria for invasion, there is not universal agreement in what constitutes capsular invasion, angioinvasion and extrathyroidal invasion. Irrespective of the discrepant views on invasion, pathologists should report on the presence and extent (focal, widely) of capsular invasion, angioinvasion and extrathyroidal extension. These findings assist clinicians in their assessment of the recurrence risk and potential for metastatic disease. It is beyond the scope of this paper to detail the entire CAP protocol for thyroid carcinomas; rather, this paper addresses some of the more problematic issues confronting pathologists in their assessment and reporting of thyroid carcinomas.

Conclusion: The new CAP protocol for reporting of thyroid carcinomas is a step toward improving the clinical value of the histopathologic reporting of TC. Large meticulous clinico-pathologic and molecular studies with long term follow up are still needed in order to increase the impact of microscopic examination on the prognosis and management of TC.

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Tumor necrosis in thyroid carcinoma with various growth patterns. a Follicular growth pattern with tumor necrosis (N). b Papillary architecture with necrosis (N). c Tumor with a predominantly solid growth pattern and a large area of necrosis (N). d Tumor with an insular pattern. Necrosis was present elsewhere in the specimen. Reproduced with permission from Hiltzik et al. [14]
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Fig4: Tumor necrosis in thyroid carcinoma with various growth patterns. a Follicular growth pattern with tumor necrosis (N). b Papillary architecture with necrosis (N). c Tumor with a predominantly solid growth pattern and a large area of necrosis (N). d Tumor with an insular pattern. Necrosis was present elsewhere in the specimen. Reproduced with permission from Hiltzik et al. [14]

Mentions: Increased mitotic activity and especially tumor necrosis are powerful indicators of adverse outcome in thyroid carcinomas of follicular origin. Asklen and Livolsi showed that tumor necrosis and mitotic rate >2 mitosis/10 high power fields indicate worse survival in papillary thyroid carcinoma (P = 0.028; P < 0.00005, respectively) [15]. Mitosis and tumor necrosis are also strongly associated with poorly differentiated thyroid carcinomas (PDTC). The latter type of carcinoma has a prognosis in between the indolent well differentiated papillary thyroid carcinomas and the almost universally lethal anaplastic carcinoma. Its definition is however subject to controversy. PDTC defined on the basis of high mitotic activity (≥5 mitosis/10 high power fields, 400×) and/or tumor necrosis have a disease specific survival of 60% at 5 years irrespective of the tumor architecture (Fig. 4) [16]. PDTC defined mainly on the basis of growth pattern alone (such as the tumors reported in the large Italian study by Volante et al.) also occupy an intermediate position at the prognostic level on the spectrum of thyroid carcinoma progression [17]. However, when Volante et al. developed a numeric scoring system whose most influential parameter was tumor necrosis, those neoplasms with necrosis had a much worse survival than those without [17]. Indeed, the overall survival curve of their most favorable subgroup even overlapped with that of patients with well-differentiated papillary and follicular carcinomas [17]. The overall survival of their most aggressive group (those patients whose neoplasms contained at least tumor necrosis) appears to be closer to that of PDTC defined by necrosis and/or a high mitotic rate [17]. Recently, a group of pathologists gathered in Turin, Italy in the attempt to provide a consensus view regarding PDTC [18].Their definition relied on the presence of solid growth but required the presence of at least one of the followings: convoluted nuclei, tumor necrosis and/or mitosis ≥3/10 high power fields, 400×. In this study as well, mitosis and tumor necrosis were very powerful indicator of poor outcome (P = 0.011; P < 0.001 respectively) while the type of PDTC (papillary vs non-papillary) was not. The value of mitosis and tumor necrosis is also emphasized by the fact that PDTC defined on the basis of mitoses and/or necrosis is the major cause of radioactive iodine (RAI) refractory, positron emission tomography (PET)-positive incurable thyroid carcinomas [19]. The importance of tumor necrosis in primary tumors is further validated by the fact that it was (along with extra-thyroid extension) the only independent variable associated with decreased overall survival within RAI refractory thyroid carcinomas [19].Fig. 4


Update to the College of American Pathologists reporting on thyroid carcinomas.

Ghossein R - Head Neck Pathol (2009)

Tumor necrosis in thyroid carcinoma with various growth patterns. a Follicular growth pattern with tumor necrosis (N). b Papillary architecture with necrosis (N). c Tumor with a predominantly solid growth pattern and a large area of necrosis (N). d Tumor with an insular pattern. Necrosis was present elsewhere in the specimen. Reproduced with permission from Hiltzik et al. [14]
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2807537&req=5

Fig4: Tumor necrosis in thyroid carcinoma with various growth patterns. a Follicular growth pattern with tumor necrosis (N). b Papillary architecture with necrosis (N). c Tumor with a predominantly solid growth pattern and a large area of necrosis (N). d Tumor with an insular pattern. Necrosis was present elsewhere in the specimen. Reproduced with permission from Hiltzik et al. [14]
Mentions: Increased mitotic activity and especially tumor necrosis are powerful indicators of adverse outcome in thyroid carcinomas of follicular origin. Asklen and Livolsi showed that tumor necrosis and mitotic rate >2 mitosis/10 high power fields indicate worse survival in papillary thyroid carcinoma (P = 0.028; P < 0.00005, respectively) [15]. Mitosis and tumor necrosis are also strongly associated with poorly differentiated thyroid carcinomas (PDTC). The latter type of carcinoma has a prognosis in between the indolent well differentiated papillary thyroid carcinomas and the almost universally lethal anaplastic carcinoma. Its definition is however subject to controversy. PDTC defined on the basis of high mitotic activity (≥5 mitosis/10 high power fields, 400×) and/or tumor necrosis have a disease specific survival of 60% at 5 years irrespective of the tumor architecture (Fig. 4) [16]. PDTC defined mainly on the basis of growth pattern alone (such as the tumors reported in the large Italian study by Volante et al.) also occupy an intermediate position at the prognostic level on the spectrum of thyroid carcinoma progression [17]. However, when Volante et al. developed a numeric scoring system whose most influential parameter was tumor necrosis, those neoplasms with necrosis had a much worse survival than those without [17]. Indeed, the overall survival curve of their most favorable subgroup even overlapped with that of patients with well-differentiated papillary and follicular carcinomas [17]. The overall survival of their most aggressive group (those patients whose neoplasms contained at least tumor necrosis) appears to be closer to that of PDTC defined by necrosis and/or a high mitotic rate [17]. Recently, a group of pathologists gathered in Turin, Italy in the attempt to provide a consensus view regarding PDTC [18].Their definition relied on the presence of solid growth but required the presence of at least one of the followings: convoluted nuclei, tumor necrosis and/or mitosis ≥3/10 high power fields, 400×. In this study as well, mitosis and tumor necrosis were very powerful indicator of poor outcome (P = 0.011; P < 0.001 respectively) while the type of PDTC (papillary vs non-papillary) was not. The value of mitosis and tumor necrosis is also emphasized by the fact that PDTC defined on the basis of mitoses and/or necrosis is the major cause of radioactive iodine (RAI) refractory, positron emission tomography (PET)-positive incurable thyroid carcinomas [19]. The importance of tumor necrosis in primary tumors is further validated by the fact that it was (along with extra-thyroid extension) the only independent variable associated with decreased overall survival within RAI refractory thyroid carcinomas [19].Fig. 4

Bottom Line: While there are defined criteria for invasion, there is not universal agreement in what constitutes capsular invasion, angioinvasion and extrathyroidal invasion.These findings assist clinicians in their assessment of the recurrence risk and potential for metastatic disease.Large meticulous clinico-pathologic and molecular studies with long term follow up are still needed in order to increase the impact of microscopic examination on the prognosis and management of TC.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, 10065, New York, NY, USA. ghosseir@mskcc.org

ABSTRACT

Background: The reporting of thyroid carcinomas follows the recommendations of the College of American Pathologists (CAP) protocols and includes papillary carcinoma, follicular carcinoma, anaplastic carcinoma and medullary carcinoma. Despite past and recent efforts, there are a number of controversial issues in the classification and diagnosis of thyroid carcinomas (TC) that, potentially impact on therapy and prognosis of patients with TC.

Discussion: The most updated version of the CAP thyroid cancer protocol incorporates recent changes in histologic classification as well as changes in the staging of thyroid cancers as per the updated American Joint Commission on Cancer staging manual. Among the more contentious issues in the pathology of thyroid carcinoma include the defining criteria for tumor invasiveness. While there are defined criteria for invasion, there is not universal agreement in what constitutes capsular invasion, angioinvasion and extrathyroidal invasion. Irrespective of the discrepant views on invasion, pathologists should report on the presence and extent (focal, widely) of capsular invasion, angioinvasion and extrathyroidal extension. These findings assist clinicians in their assessment of the recurrence risk and potential for metastatic disease. It is beyond the scope of this paper to detail the entire CAP protocol for thyroid carcinomas; rather, this paper addresses some of the more problematic issues confronting pathologists in their assessment and reporting of thyroid carcinomas.

Conclusion: The new CAP protocol for reporting of thyroid carcinomas is a step toward improving the clinical value of the histopathologic reporting of TC. Large meticulous clinico-pathologic and molecular studies with long term follow up are still needed in order to increase the impact of microscopic examination on the prognosis and management of TC.

Show MeSH
Related in: MedlinePlus