Postirradiation sarcomatous transformation of a pituitary adenoma: a combined pituitary tumor. Case report.

A case is reported in which a fibrosarcoma developed 20 years after irradiation of a pituitary chromophobe adenoma. This rare lesion, like most of the other documented postirradiation pituitary sarcomas, was a combination of fibrosarcoma and pituitary adenoma. These lesions tend to behave in a characteristic fashion, with onset after a long latent interval following irradiation, growth to a large size, and failure to metastasize.