Diagnosis: Anaplastic thyroid carcinoma
• Histologic examination of anaplastic thyroid carcinomas usually shows sheets of large bizarre cells. Tumoral giant cells may be seen.
• Numerous mitotic figures are typically evident, as well as necrosis and vascular invasion.
• Squamoid” or “sarcomatoid” features are frequently identified.
• The immunohistochemical properties of anaplastic carcinoma are variable. These tumors are usually cytokeratin-positive and thyroglobulin-negative. “Positive” thyroglobulin staining, if present, generally occurs in only a few scattered cells.
• Calcitonin staining may be found in tumors that have apparently arisen within medullary carcinoma.
