Medullary thyroid carcinoma with diabetic ketoacidosis: an autopsy case report and literature review.

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor of parafollicular C cells. The majority of MTCs occur sporadically, but about 30% of the cases are associated with multiple endocrine neoplasia type 2 (MEN2) syndrome or familial MTC. Generally, MTCs have no clinical manifestation, but infrequently the patients develop symptoms of hypercortisolism by secreting adrenocorticotropic hormone (ACTH) or corticotropin-releasing hormone (CRH). Although ectopic Cushing syndrome is only found in 0.7% of MTC patients, it can lead to fatal consequences if left untreated. Over 50 cases of MTC-related Cushing syndrome have been reported, and few autopsy cases exist in the literature. In those cases, the tumor cells are positive for calcitonin, but mostly display negative immunostaining for ACTH or CRH. The authors report an autopsy case of a 22-year-old woman who was found dead with no medical history whose cause of death was diabetic ketoacidosis associated with MTC, which showed poor calcitonin stainability.