DIAGNOSIS AND TREATMENT OF PATIENTS WITH PARATHYROID CARCINOMA - AN UPDATE AND REVIEW

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. However, to our best knowledge, at least 163 cases of functioning parathyroid carcinoma appeared in the English literature from 1981 to 1989. We summarize the available information obtained from the reports of those patients and compare it with previous descriptions of the disease. The etiology of parathyroid carcinoma is usually obscure, but the possibility of a radiation-induced malignant change in the parathyroid gland became evident in a few patients. Clinical manifestations, including age, sex, symptoms, and biochemical findings in this review were comparable to those in previous reviews. Noninvasive localization studies such as ultrasonography may offer a diagnostic clue to parathyroid carcinoma. Measurement of DNA content is a useful adjunct for making the histologic diagnosis of parathyroid carcinoma and prediction of the clinical outcome. Since the initial operation offers the best chance for cure, preoperative suspicion and intra-operative recognition of the parathyroid cancer are essential. The initial operation should be en bloc resection of the tumor, avoiding rupture of the tumor capsule and spillage of tumor cells. As parathyroid carcinoma is a slow-growing but tenacious malignancy, repeated resection of local recurrent tumors or even distant metastases is effective for palliation of recurrent hypercalcemia and occasional cure. When hypercalcemia is refractory to surgical therapy or no recurrent tumor can be identified, other modalities of therapy must be considered. New drugs to control hypercalcemia by inhibiting bone resorption may hold promise in patients with recurrent parathyroid carcinoma.