[Pituitary oncocytoma].

Since the first reports of pituitary oncocytoma by Kovacs and Horvath, and Landolt and Oswald increasing numbers of cases have been reported with the advent of electron microscopy. It has been posturated that more cases were not precisely diagnosed because of lack of electron microscopic study. We reported two cases of pituitary oncocytoma and discussed clinicopathological aspects. Case 1 A 66-year-old woman had a 6 year history of visual impairment. Neurological examination revealed loss of vision on the left and decreased visual acuity (0.3) with temporal hemianopsia on the right. The endocrinological study revealed moderate panhypopituitarism. Plain skull X-ray, computed tomography and cerebral angiography showed the findings of a pituitary tumor with suprasellar extension. Subfrontal removal of the tumor followed by irradiation was performed. Case 2 A 50-year-old man was well until 8 years previously, when he experienced loss of libido. Three years before entry, the left sided exophthalmos and ptosis were noted. Neurological examination showed a severe visual impairment with a bitemporal field defect, bilateral optic atrophy and disturbance of eye movements on the left. Endocrinological study revealed panhypopituitarism. Radiological studies showed a pituitary tumor with a suprasellar extension and an invasion into the left orbital cavity. Transcranial and then transsphenoidal partial removal of the tumor were done followed by irradiation. Histological examination of the tumors revealed a poorly granurated adenoma with very weak affinity to acid dyes.(ABSTRACT TRUNCATED AT 250 WORDS)