Parathyroid carcinoma with anaplastic feature: association of a p53 gene mutation with anaplastic transformation.

Parathyroid carcinoma is a rare neoplasm that accounts for only 1-3% of cases of primary hyperparathyroidism. Parathyroid carcinoma is a well-differentiated tumor that is sometimes difficult to differentiate histopathologically from its benign counterpart, parathyroid adenoma. The molecular mechanism of parathyroid carcinogenesis remains unknown, and investigators have reported that abnormalities of the p53 gene do not play a significant role in parathyroid carcinogenesis, unlike in other human malignancies. The present report describes parathyroid carcinoma with anaplastic transformation of differentiated parathyroid carcinoma in a patient with primary hyperparathyroidism. Nuclear accumulation of p53 protein was found in anaplastic carcinoma cells but not in differentiated carcinoma cells. Polymerase chain reaction-single-strand conformation polymorphism followed by direct sequencing showed that anaplastic carcinoma cells carried a missense mutation at codon 248 (CGG to CAG) of the p53 gene, while the remaining differentiated carcinoma cells had the wild-type p53 gene. These findings suggest that the p53 gene mutation is associated with anaplastic transformation of parathyroid carcinoma.