Sarcomatous change after sellar irradiation in a growth hormone-secreting pituitary adenoma

Background. Although the benefits of radiotherapy for pituitary adenomas are well-documented, post-irradiation sarcomas of the sella are rarely seen, with only 20 cases (mainly of fibrosarcoma) reported in the medical literature. Method: We describe a case of post-irradiation sarcoma five years after surgery followed by external-beam irradiation for an extensive and locally invasive growth hormone-secreting tumor. The patient was subsequently given pegvisomant, an antagonist of growth hormone receptor, to control symptoms of growth hormone excess. Results: The patient underwent transsphenoidal resection of the recurrent tumor, followed by adjuvant chemotherapy. This led to significant relief in the patient's symptoms including radiological evidence of tumor shrinkage, but the tumor regrew when, owing to dose-limiting toxicity, chemotherapy was stopped. Conclusions: Post-irradiation sarcomas of the pituitary are well-recognized but rare. They should be suspected in patients following sellar irradiation who show abrupt onset of new symptoms and appropriate radiological findings, and such tumors may respond to cytotoxic chemotherapy.