Post-irradiation pituitary sarcoma.

A fibrosarcoma developed in the pituitary fossa of a patient who had been irradiated 13 years previously for treatment of pituitary adenoma. The tumor was a large aggressively growing spindle cell neoplasm which eroded adjacent structures, causing increased intracranial pressure, and eventual cerebellar tonsillar herniation. In common with previously described post-irradiation sarcoma of the pituitary, this lesion developed in the path of irradiation after a long latent period, did not metastasize, and contained histologically recognizable benign appearing pituitary adenoma interspersed among the spindle cell tumor. The dose of radiation (5000 rads) also lay within the range associated with sarcomatous transformation.