Immunohistochemical study of crooke's hyaline change

Crooke's hyaline change of the human pituitary gland appears as an intracytoplasmic accumulation of fine filaments under electron microscopy. This study was attempted to identify the fine filaments by immunohistochemical methods. Twenty-eight postmortem, formalin-fixed or chrome-alum-fixed, paraffin-embedded pituitary glands revealing unequivocal Crooke's hyaline change on hematoxylin and eosin stain were selected for this study. To demonstrate Crooke's cells and fine filaments simultaneously, mirror image sections were sliced and stained with the following monoclonal antibodies using an avidin-biotin-peroxidase complex method: an antibody against synthesized adrenocorticotropic hormone 1-24, human cytokeratins (55-57 kilodalton [kd] and 68 kd), porcine vimentin (57 kd), porcine desmin (53 kd), bovine neurofilaments (70, 160, and 210 kd), human glial fibrilfary acidic protein (GFAP) (56 kd), and chicken actin. Crooke's cells showed a variable intensity of cytoplasmic staining for 55- to 57-kd cytokeratins, from focal to more even and intense staining revealing a characteristic wide brown ring around the nucleus or beneath the cell membrane. The most severely affected cells were totally replaced by dark brown reaction products with no secretory granules detectable in the cytoplasm. However, 68-kd cytokeratin could not be unequivocally demonstrated. Crooke's cells were all negative for vimentin, desmin, neurofilaments, GFAP, and actin. Thus far, it could be concluded that Crooke's hyaline change was composed of intermediate-subunit molecular weight cytokeratins that are normal constituents of the ACTH cell.