Hyperfunctional parathyroid carcinoma with mediastinal extension.

Parathyroid carcinoma (PC) is an extremely rare malignancy, 0.005% of all tumours and between 0.5% and 5% of all parathyroid neoplasms. Preoperative diagnosis is often difficult and is almost always obtained only after post-surgical histopathology. The prognosis is related to the local extent of disease and to complete surgical resection of the tumour. We report an uncommon case of hyperfunctional PC with mediastinal extension, emphasising the diagnostic difficulties, histopathological features and treatment strategies. The most recent data in the literature is analysed as well.