PITUITARY-ADENOMA WITH CHOLESTEROL CLEFTS

Histologically, cholesterol clefts are often observed in craniopharyng ioma, Rathke's cleft cyst, and various granulomas. However, pituitary adenomas with cholesterol clefts are rare. A 46-year-old woman develop ed visual field disturbance. She had no history of severe headache tha t would suggest pituitary apoplexy. She presented with homonymous bite mporal hemianopsia and galactorrhea. Blood prolactin level was 63.1 ng /mL. Other hypophysial hormone levels were within normal range. Magnet ic resonance imaging revealed a pituitary tumor with intratumoral cyst . The cyst showed high intensity on T1- and T2-weighted images. The tu mor was demonstrated with iso intensity on T1-weighted image and with high intensity on T2-weighted image. She underwent trans-sphenoidal su rgery. The tumor was soft, with yellowish, oily fluid, probably the cy st content. By light microscopy with hematoxylin and eosin staining, a typical chromophobic adenoma of the pituitary was identified. Immunos taining revealed immunoreactivity for ACTH in several cells. Many chol esterol clefts and several hemosiderin pigment containing macrophages were observed. Electron microscopy demonstrated a pituitary adenoma wi th sparse and small secretory granules and numerous lysosomes. The cys t was most likely caused by focal hemorrhagic infarction, followed by the formation of cholesterol crystals, the appearance of hemosiderin c ontaining macrophages, foreign body product cells, and accumulation of lysosomes.