Parathyroid adenocarcinoma.

Parathyroid adenocarcinoma is a very rare carcinoma with an equal male-female incidence. The clinical picture that adenocarcinoma of the parathyroid presents is the same as that of hyperparathyroidism due to adenoma. Onset of parathyroid adenocarcinoma occurs primarily in the fourth decade of life. It is not incompatible with long-term survival provided that the entire gland is removed at the initial operation without rupture of the capsule. If the carcinoma recurs, it grows slowly and any spread tends to be local. Distant metastasis is rare. Calcium levels above 13 mg/100 mL should alert the clinician to the possibility of adenocarcinoma of the parathyroid. Increased mitotic figures, increased fibrosis of the gland, and invasion of the vessels and surrounding tissues are the features indicative of malignancy. A review of the literature reveals that fewer than 150 cases of this entity have been reported. The authors present two case reports and discuss the epidemiology, clinical picture, pathology, and therapy of parathyroid adenocarcinoma.