Aggressive Forms of Follicular-derived Thyroid Carcinoma

Although most follicular-derived thyroid carcinomas are well differentiated and have an excellent prognosis, certain forms of thyroid carcinoma behave in a clinically more aggressive fashion. We present a case of a 27-year-old woman who presented with a palpable, 3.0-cm right thyroid nodule. Fine needle aspiration showed a cellular lesion with many crowded groups of small follicular cells with scant cytoplasm, clumped chromatin, moderate nuclear pleomorphism, and mitotic activity. Surgical resection of the thyroid gland revealed an insular carcinoma with classic nested architecture arising within a microfollicular thyroid neoplasm. Two years later, the patient developed multiple liver nodules detected by computed tomography, and fine needle aspiration showed metastatic insular carcinoma. Insular carcinoma, in particular, as well as certain subtypes of papillary carcinoma, such as the tall cell, columnar cell, and diffuse sclerosing variants, is considered to be an aggressive form of follicular-derived carcinoma. Its clinical behavior is between that of well differentiated thyroid carcinoma and of anaplastic carcinoma, the most highly aggressive follicular-derived malignancy arising within the thyroid gland. Cytologic and histologic recognition of these aggressive variants of thyroid carcinoma is important because the specific diagnosis may impact the clinical management of these patients.