Squamous cell carcinoma (SQC) accounts for < 1% of thyroid cancers. It occurs in the elderly and has a dismal prognosis. FNA smears are composed almost exclusively of large, pleomorphic keratinized cells. Necrosis may be present. Differential diagnosis include UTC and metastatic squamous cell carcinoma.
Metastatic Tumors and Lymphomas
Metastases from distant organs and direct extension of neoplasms from adjacent structures are not common but must be recognized in fine needle aspiration
(FNA) samples of thyroid nodules. In rare cases, a metastasis to the thyroid can even be the initial presentation of a distant malignancy.
Metastatic carcinomas are present in one of three patterns multiple small