Two cases of pituitary Crooke's cell adenoma without Cushing's disease: A histologic, immunocytochemical, electron microscopic and in situ hybridization study

Presented herein are the morphologic features of two cases of pituitary Cro oke's cell adenoma unassociated with Gushing's disease. Both were removed s urgically, one from a 62-yr-old woman and the other from a 37-yr-old man. C rooke's cell adenomas are rare. All previously published cases were associa ted with clinical and laboratory evidence of Gushing's disease. The two cas es presented here are the first that were unaccompanied by adrenocorticotro pin (ACTH)-cortisol excess. Crooke's cell adenomas are composed of abnormal corticotrophs containing periodic acid-Schiff- (PAS) negative, ACTH-immuno negative, and keratin-immunoreactive cytoplasmic microfilaments filling lar ge areas of the cytoplasm and displacing other organelles. Adenomatous Croo ke's cells express proopiomelanocortin (POMC) mRNA. The question of whether the absence of ACTH-cortisol hypersecretion in our two cases is mediated v ia functioning glucocorticoid receptors in the adenoma cells or whether oth er mechanisms are involved remains to be elucidated.