Prognostic indicators in an aggressive pituitary Crooke's cell adenoma.

OBJECTIVE: To investigate prognostic indicators in an aggressive Crooke's cell adenoma of the pituitary. METHODS: The surgically removed tumor was studied by histology, immunohistochemistry and transmission electron microscopy. RESULTS: An aggressive invasive sellar tumor removed by repeated surgeries from a 43-year-old woman with pituitary related Cushing's disease was classified as a Crooke's cell adenoma of the pituitary. The application of several cell proliferation markers confirmed the aggressive nature of the tumor. CONCLUSIONS: The investigation of the present case provides additional evidence that pituitary Crooke's cell adenomas may possess aggressive behavior.