Hyperparathyroidism after radiation of the head and neck: a case report and review of the literature.

A 66-year-old woman presented with hypercalcemia and a past history of external radiation to the neck. Hyperparathyroidism in this patient was caused by a parathyroid adenoma. The literature associating hyerparathyroidism with prior radiation of the head and neck was reviewed and analyzed. Current evidence supports a relationship between external radiation of the head or neck and the development of hyperparathyroidism as a late complication. Analysis of data available suggests that radiation-association hyperparathyroidsim develops after an average latent period of 38 years. Parathyroid adenoma occurred more often than did hyperplasia. Parathyroid carcinoma has not been reported in irradiated patients with hyperparathyroidsim. Neither age at radiation exposure, age at diagnosis of hyperparathyroidsim, nor interval between exposure and diagnosis was associated with a specific histologic diagnosis (adenoma or hyperplasis).