Parathyroid carcinoma

A rare endocrine tumor characterized by a malignant neoplasm derived from parathyroid parenchymal cells, localized in one of the normally located parathyroid glands or other sites where parathyroid tissue may be present. Signs and symptoms are predominantly due to excess secretion of parathyroid hormone, with marked hypercalcemia and renal and bone involvement. In rare cases, the tumor may be non-functioning and only present as a palpable mass in the neck region. Recurrent laryngeal nerve paralysis is also observed. The tumor can occur sporadically or on a genetic background. The extent of invasion of adjacent structures positively correlates with the development of recurrent or metastatic disease.