The coexistence of parathyroid adenoma and thyroid carcinoma.

Not well-known and inadequately understood is the high incidence of conexistent parathyroid adenoma and nonmedullary thyroid carcinoma. In a series of 144 patients with parathyroid adenoma, 11 (8%) were found to have concurrent thyroid carcinoma. Although similar to other multiple endocrine tumor syndromes, these two tumors have no common embryologic cell origin. The most likely explanation for this apparent relationship is the specific oncogenic effect of hypercalcemia on the thyroid gland.