The pituitary gland in untreated Addison's disease. A histologic and immunocytologic study of 18 adenohypophyses.

The pituitary glands of 18 patients with untreated Addison's disease were studied by histologic and immunocytochemical methods. Adrenal destruction was caused by tuberculosis (13 cases) or autoimmune adrenalitis (five cases), and the duration of the adrenal insufficiency ranged from one to 16 years. Both diffuse and nodular hyperplasia of corticotropic cells were evident in each case, and the extent of hyperplasia correlated with the duration of disease. In five cases, nodular proliferations with morphologic features between those of hyperplasia and those of adenoma, termed tumorlets, were identified, as were two microadenomas, only one of which was available for study. In all instances, the proliferating corticotrophs stained positively with PAS and were immunoreactive for adrenocorticotropic hormone and beta-endorphin. We conclude that diffuse and nodular corticotroph hyperplasia are common in untreated Addison's disease, although frank adenoma formation seems to be rare. The latter may be related to the short duration of disease or may imply the absence of additional, unknown factors that are required for adenoma growth.