A 42-year-old woman has noted increasing fullness in her neck for the past 7 months. On physical examination, her thyroid gland is diffusely and asymmetrically enlarged and nodular. There is no lymphadenopathy. She undergoes thyroidectomy. Gross examination of the thyroid shows a multicentric thyroid neoplasm; microscopically, the neoplasm is composed of polygonal-to spindle-shaped cells forming nests and trabeculae. There is a prominent, pink hyaline stroma that stains positively with Congo red. Electron microscopy shows varying numbers of intracytoplasmic, membrane-bound, electron-dense granules. Immunohistochemical staining for which of the following antigens is most useful for the diagnosis of this neoplasm?
Medullary carcinomas are derived from the C cells, or parafollicular cells, of the thyroid, with embryologic origin from the neural crest. Therefore they have the neuroendocrine function, including synthesis of calcitonin. An amyloid stroma is a common feature of this tumor. These tumors occur sporadically in about 70% of cases, but they can be familial and part of multiple endocrine neoplasias types 2A and 2B. CD3 is a useful marker for some lymphoid neoplasms. Although various tissues may show positivity for estrogen receptors, this finding has no clinical significance in the thyroid. Staining for parathyroid hormone is useful to determine if a parathyroid carcinoma is present. Vimentin is a marker for sarcomatous neoplasms, and cytokeratin is a useful marker to determine if a neoplasm is epithelial.
Calcitonin
CD3
Cytokeratin
Estrogen receptor
Endocrine