Mixed squamous cell carcinoma and follicular carcinoma of the thyroid gland

Multiple squamous cells in thyroid fine needle aspiration: Friends or foes?

“…In some cases, the squamous metaplasia can be so extensive, so as to raise the suspicion of papillary thyroid carcinoma . Reparative epithelial changes in thyroid cysts were addressed by Faquin et al The malignant entities reported as presenting with squamous cells on an aspirate smear most likely represent malignant transformation of follicular epithelial cells . Gopal et al note the presence of cytologically bland‐appearing squamous cells on histologic sections from anaplastic spindle cell squamous carcinoma cases, which could theoretically be a diagnostic pitfall on an aspirate .…”

“…9 Reparative epithelial changes in thyroid cysts were addressed by Faquin et al 10 The malignant entities reported as presenting with squamous cells on an aspirate smear most likely represent malignant transformation of follicular epithelial cells. 11,12 Gopal et al note the presence of cytologically blandappearing squamous cells on histologic sections from anaplastic spindle cell squamous carcinoma cases, which could theoretically be a diagnostic pitfall on an aspirate. 13 Similarly, Baloch et al found nests of epidermoid or squamous cells on tissue sections of sclerosing mucoepidermoid carcinomas with eosinophilia, which can be difficult to interpret on cytology.…”

Combined Squamous Cell Carcinoma and Follicular Carcinoma of the Thyroid

“…Histologic examination showed a poorly differentiated squamous cell carcinoma mixed with follicular carcinoma. Despite the development of a metastatic follicular carcinoma in the right iliac crest 3 years after surgery, the patient survived more than 6 years after surgery [ 2 ]. The different biologic behaviors displayed by PSCCT and mixed squamous cell carcinoma and follicular carcinoma are not fully understood, but they could be related to the presence of follicular carcinoma as a barrier.…”

“…Because squamous cells are absent from the normal thyroid gland, the etiology of PSCCT remains unclear. Hypotheses include the differentiation of squamous cells derived from embryonic remnants of epithelial cells in the gland, squamous metaplastic changes in response to inflammatory diseases such as thyroiditis, and malignant neoplasms, such as papillary, follicular, or anaplastic carcinoma [ 2 ]. Occasionally, PSCCT arises from other thyroid diseases such as Hashimoto’s thyroiditis, tall cell variant papillary carcinoma, follicular carcinoma, and anaplastic carcinoma [ 3 , 4 ].…”

“…We describe a patient with the combination of a well-differentiated squamous cell carcinoma and follicular carcinoma of the thyroid. To our knowledge, this is the third report of a patient with primary squamous cell carcinoma plus follicular carcinoma of the thyroid in the English language literature [ 2 , 5 ].…”