Fatal sporadic medullary carcinoma of the thyroid.

Thirteen cases of fatal sporadic medullary carcinoma of the thyroid (MCT) that killed the patient within 1 year after diagnosis were compared with 12 nonfatal MCTs with excellent prognosis. Males predominated in fatal cases whereas the reverse was true in MCTs with good prognosis. The two groups of tumors showed generally similar cytoarchitectural features. Outstanding features of fatal MCTs, as compared with nonfatal ones, included more cellular atypia, less frequent amyloid stroma and calcification, higher mitotic rate, tumor necrosis, and a generally lower proportion of neoplastic cells stained for calcitonin. We believe that the morphological features based on routine histological studies, together with immunohistochemistry, should be reported by the pathologist since they could be useful for the management and follow-up of patients with MCT.