Squamous cell carcinoma of the thyroid gland: primary or secondary disease?
ABSTRACT To review the aetiopathogenesis, clinical characteristics, immunohistochemical profile, prognosis and treatment options for primary thyroid squamous cell carcinoma, and to compare it with squamous cell carcinoma metastatic to the thyroid, thus providing the reader with a framework for differentiating primary and secondary disease.
Review of English language literature from the past 25 years.
A search of the Medline, Embase and Cochrane databases (April 1984 to April 2009) was undertaken to enable a comprehensive review.
After applying strict criteria for the diagnosis of primary thyroid squamous cell carcinoma, 28 articles were identified reporting 84 cases. When reviewing secondary thyroid squamous cell carcinoma, we only analysed cases of squamous cell carcinoma metastatic to the thyroid gland, and found 28 articles reporting 78 cases.
It is possible to differentiate between primary and secondary thyroid squamous cell carcinoma, on the basis of combined evidence from clinical examination and endoscopic, pathological and radiological evaluation. Such differentiation is important, as the prognosis for primary squamous cell carcinoma is uniformly poor irrespective of treatment, and the most suitable option may be supportive therapy. Treatment for secondary squamous cell carcinoma of the thyroid varies with the site and extent of spread of the primary tumour.
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ABSTRACT: A case of primary squamous-cell carcinoma (SCC) of the thyroid which had been initially diagnosed as an anaplastic carcinoma (ATC) is described: female, 73 years old, with a fast-growing cervical nodule on the left side and hoarseness for 3 months. Ultrasonography showed a 4.5 cm solid nodule. FNA was compatible with poorly differentiated carcinoma with immunoreactivity for AE1/AE3, EMA.Thyroidectomy was performed. Histopathological examination showed a nonencapsulated tumor. Immunohistochemistry disclosed positivity for AE1/AE3, p53,p63, and Ki67. The diagnosis was ATC. A second opinion reported tumor consisting of squamous cells, with intense inflammatory infiltrate both in tumor and in the adjacent thyroid, with final diagnosis of SCC, associated with Hashimoto thyroiditis. No other primary focus of SCC was found. Patient has shown a 48- month survival period. Clinically, primary SCCs of the thyroid and ATCs are similar. The distinction is often difficult particularly when based on the cytological analysis of FNA material.09/2014; 2014. DOI:10.1155/2014/301780
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ABSTRACT: Anaplastic thyroid carcinoma can be difficult to diagnose because it does not show thyroid differentiation morphologically or immunohistochemically. Depending on the histologic variant, anaplastic thyroid carcinoma may be confused with sarcoma or squamous cell carcinoma of the head and neck. PAX8 is a transcription factor expressed in normal and neoplastic thyroid follicular epithelium and only a few other tissues. This restricted expression suggests that PAX8 staining could be useful when dealing with spindled or squamoid tumors of the neck. The purposes of this study were to determine the frequency of PAX8 staining in anaplastic thyroid carcinoma and to evaluate PAX8 immunohistochemistry as a means of distinguishing its squamoid variant from head and neck squamous cell carcinoma. PAX8 immunohistochemical staining was performed on 34 anaplastic thyroid carcinomas and 118 head and neck squamous cell carcinomas. PAX8 staining was present in 26 (76%) anaplastic thyroid carcinomas including 16 (100%) of 16 squamoid variants, 7 (58%) of 12 giant cell/pleomorphic variants, and 3 (50%) of 6 spindled variants. All head and neck squamous cell carcinomas were negative for PAX8. PAX8 expression is often retained in anaplastic thyroid carcinomas including the squamoid variant, but it is not expressed in head and neck squamous cancers. PAX8 staining is an excellent marker for carcinomas of follicular epithelial origin, including those carcinomas that are undifferentiated in other respects. The tissue specificity of PAX8 expression may be useful in resolving the differential diagnosis of anaplastic thyroid carcinoma such as the distinction between its squamoid variant and squamous cell carcinoma of the head and neck.Human pathology 06/2011; 42(12):1873-7. DOI:10.1016/j.humpath.2011.02.004 · 2.81 Impact Factor
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ABSTRACT: KIT, a tyrosine kinase receptor protein encoded by the proto-oncogene c-kit, is overexpressed in human neoplasms such as gastrointestinal stromal tumors and thymic squamous cell carcinoma. However, the role of KIT expression and mutations in carcinoma showing thymus-like elements is not fully understood. In the current study, 8 cases of carcinoma showing thymus-like elements were reported, and immunohistochemical staining with KIT and CD5 was performed. Mutation analyses in the juxtamembrane domains (exons 9 and 11) and in the tyrosine kinase domains (exons 13 and 17) were performed on KIT-positive samples using polymerase chain reaction and direct DNA sequencing. KIT- and CD5-positive stainings were observed in all 8 cases. However, none of the tested samples showed mutations in any of the 4 exons. The primary carcinoma showing thymus-like elements of the thyroid frequently expresses KIT and CD5 proteins; similar to thymic squamous cell carcinoma, the overexpression of KIT does not necessarily indicate a gene mutation in this tumor. KIT, along with CD5, could be a useful marker for the difficult diagnosis of carcinoma showing thymus-like elements, which should be added to the list of KIT-positive neoplasms.Human pathology 08/2011; 43(3):350-5. DOI:10.1016/j.humpath.2011.05.003 · 2.81 Impact Factor