Synchronous sporadic carcinoma and primary hyperplasia of the parathyroid glands: A case report and review of the literature.

Parathyroid carcinoma is the least common endocrine malignancy. Although it has been noted to be associated with certain clinical factors, such as familial hyper-parathyroidism, its etiology remains unknown. In rare instances, particularly in patients with chronic renal failure, it has been proposed that parathyroid carcinoma can arise from malignant transformation of benign lesions. We present a case of synchronous malignant and primary hyperplastic parathyroid disease in a patient with normal renal function. A 46-year-old woman was seen with symptomatic refractory hypercalcemia. Investigations suggested a hyperactive parathyroid gland. Operative findings were of a low-grade parathyroid carcinoma in concurrence with diffuse hyperplasia of the remaining glands. To our knowledge this represents the fifth reported case. The possibility of malignant change in hyperplastic parathyroid tissue has implications for patient management and follow-up, particularly if tissue is left in situ to maintain hormonal function.