Parathyroid carcinoma: A report of six cases with a brief review of the literature.

Parathyroid carcinoma (PC) is an uncommon endocrine malignancy and constitutes a rare cause of hyperparathyroidism. The current study presents the clinical features, laboratory findings, sensitivity of imaging modalities, surgical treatment and the long-term outcome of six patients, who were diagnosed with PC and treated in the Department of Head and Neck Surgery, Zhejiang Province Cancer Hospital (Hangzhou, China) over 13 years (February 1999-January 2012). Pre-operative recognition and intraoperative identification of this rare endocrine malignancy is extremely important, but require a high index of clinical suspicion. The primary treatment is surgical en bloc resection of the tumor and any involved surrounding structures, and it is of great importance, as the prognosis depends on the initial surgery. Radiation therapy and chemotherapy showed no evidence of effectiveness on PC, although certain data show a decreased risk of localized disease recurrence with the addition of radiation therapy. The prognosis of PC is variable and post-operative parathyroid hormone levels that do not decrease often indicate a poor prognosis or presence of other metastases.