Parathyroid carcinoma; a cause of recurrent primary hyperparathyroidism a few years after removal of a parathyroid adenoma.

This is a case report of recurrent hyperparathyroidism due to parathyroid carcinoma. Primarily a neck exploration revealed an adenoma of the inferior right parathyroid body but at cervical re-exploration 4 years later due to recurrence a parathyroid carcinoma at the opposite side was found. The importance of recognizing the malignancy at operation is emphasized and the author's opinion for the necessity of localizing studies in cases of reoperations at the neck for over-functioning parathyroid glands is expressed.