Non-functioning parathyroid carcinoma: a case report.

Non-functioning parathyroid carcinoma is a very rare disease. Only 12 cases have been reported in the literature. The clinical behavior is characterized by the appearance and growth of a neck mass or nodule, which often has been present for many years, and is not accompanied by clinical or laboratory evidence of hypercalcemia or elevated levels of parathyroid hormone (PTH) in peripheral blood. Pathologic findings are similar to those of functioning tumors, and the proof of malignancy is established on the basis of an increased mitotic index only. Data on survival from cases reported in the literature are not conclusive; however, the non-functioning type of parathyroid carcinoma seems to be a more aggressive disease. Radiotherapy seems to be effective in the local control of the disease, but most patients become metastatic. Even if no data are available on response to chemotherapy, the course of the disease is relatively indolent.