We report the case of a 49-year-old woman presenting with Cushing disease and visual disturbance. An atypical, aggressive, invasive pituitary tumor regrew despite several surgeries. Detailed morphologic investigation by histology, immunohistochemistry and electron microscopy documented a Crooke cell adenoma, a rare form of ACTH-producing pituitary tumor. Recognition of such adenomas is of importance given their aggressive behavior and tendency to recur. More studies are needed to explain the pathobiology of this not invariably functional pituitary adenoma.