Meningioma as a sequel of radiotherapy for pituitary adenoma.

Two cases of meningioma developing after radiation therapy of pituitary adenoma were found among 180 verified adenomas irradiated pre- or post-operatively and followed up for at least five years. Only a few instances of association of meningioma and pituitary adenoma were found in the literature. In patients who did not receive X-ray treatment both tumours were simultaneously verified at operation and/or autopsy, whereas in those who were irradiated a definite time interval, ranging from 11 to 18 years, was present between surgical and/or radiotherapeutic treatment for pituitary adenoma and verification of meningioma. A possible role of radiation in the genesis of these meningiomas is postulated.