Pituitary adenomas in Cushing's disease: do they arise from the intermediate lobe?

Pituitary adenomas from 15 patients with Cushing's disease were studied histopathologically. The tumors were examined for the presence of neural axons by the Bodian silver impregnation technique and a specific immunohistologic technique based on a monoclonal antibody to axonal neurofilaments. Axons were not seen in any of the surgical specimens. This finding suggests that most, if not all, adrenocorticotropin-secreting pituitary adenomas are of anterior lobe origin.