Pituitary histology in Cushing's disease.

Objective: We assessed pituitary histology in patients with Cushing's disease.
Design: Systematic histological assessment of pituitary tissue removed at surgery.
Patients: Thirty-six consecutive patients cured from Cushing's disease by transsphenoidal neurosurgery.
Measurements: Microscopical examination of all available tissue removed at operation.
Results: After selective removal of tissue supposed to represent an adenoma in 25 patients this could be histologically verified in 18. In the 11 patients who had undergone a total hypophysectomy an adenoma could be demonstrated in three patients only, despite a systematic search of the entire pituitary gland. Only in 21 of the 36 cured patients (58%) could an adenoma be verified.
Conclusions: Combining the present results with previous reports there is strong reason to believe that in some patients with Cushing's disease no histological lesion in the pituitary is verifiable.