Nelson's syndrome: frequency, prognosis, and effect of prior pituitary irradiation.

Previous reports differ regarding the frequency and course of pituitary tumors occurring after adrenalectomy for bilateral adrenal hyperplasia (Nelson's syndrome). In this report, 120 patients who were adrenalectomized for bilateral adrenal hyperplasia were followed for 2 to 20 years. Nine of the 120 developed Nelson's syndrome (8%), the tumors appearing 6 months to 16 years after adrenalectomy. In the majority of cases, the course was benign; seven patients are living an average of 9.7 years after discovery of their tumors. Finally, contrary to previous reports, pituitary irradiation before adrenalectomy did not prevent Nelson's syndrome. Twenty of 120 patients had pituitary irradiation as the initial treatment for bilateral adrenal hyperplasia and two subsequently developed pituitary tumors. Thus, after adrenalectomy for bilateral adrenal hyperplasia, all patients, regardless of previous pituitary irradiation, should be followed indefinitely with periodic X rays of the sella turcica for the possible occurrence of Nelson's syndrome.