Parathyroid carcinoma of the mediastinum.

Parathyroid carcinoma accounts for about 4% of all diseases of the parathyroid glands. It usually presents as a tumor mass in the neck region. Mediastinal parathyroid carcinoma has been reported very rarely. The present paper reports an ectopic parathyroid carcinoma in the anterior mediastinum in a 54-year male that failed to be recognized antemortem. The markedly elevated serum calcium levels were repeatedly put down to laboratory errors, and the clinical features of primary hyperparathyroidism were misjudged and managed only symptomatically. The terminal cardiogenic shock was associated with myocardial infarction. Coronary plastic surgery was carried out and a stent was placed. The postmortem examination found a solid elastic tumor mass (4 cm) firmly encapsulated in the upper half of the anterior mediastinum having trabecular structure, mild nuclear and cellular polymorphism, single irregular mitoses and an area of necrosis. The mass invaded the capsule and the surrounding adipose tissue, there were tumor emboli found in the lymph and blood vessels. Immunohistochemical study showed diffuse expression of low molecular weight cytokeratin, chromogranin A and synaptophysin, and more than 20% of the tumor cells were Ki-67 positive. Glycogen granules were found in their cytoplasm. There were clearly seen metastatic calcifications in the intramural coronary vessels, the cardiomyocytes, the kidneys and the lungs. The present case report contributes considerably to the differential diagnosis of hypercalcemia.