Small cell anaplastic carcinomas are rarely resected because of early metastasis.

A 40-year-old woman has noted enlargement of her anterior neck region over the past 8 months. On physical examination her vital signs include T 36.8°C， P 64/minute， RR 16/minute， and BP 155/105 mm Hg. There is diffuse， symmetrical thyroid enlargement without tenderness. A chest radiograph is normal. Fine needle aspiration of the thyroid yields cells consistent with a neoplasm. Laboratory studies show that she is euthyroid， but her serum ionized calcium is elevated. She is taken to surgery and frozen sections of several thyroid masses show a malignant neoplasm composed of polygonal cells in nests. A thyroidectomy is performed. Immunostaining for calcitonin of the permanent sections is positive， and the neoplasm has an amyloid stroma with Congo red staining. Which of the following neoplasms is she most likely to have？（ ） A: Anaplastic carcinoma B: Medullary carcinoma C: Papillary thyroid carcinoma D: Metastatic renal cell carcinoma E: Parathyroid carcinoma