Panhypopituitarism due to Rathke's cleft cyst associated with pituitary oncocytoma.

A 38-year-old male with panhypopituitarism due to Rathke's cleft cyst associated with a pituitary oncocytoma is reported. The presenting signs were general myalgia and slight fatigue. Endocrine examinations revealed panhypopituitarism. Magnetic resonance imaging disclosed a suprasellar cystic lesion of the pituitary gland. Cytological examination demonstrated ciliated cells in the mucinous fluid flowing from the cyst during the pituitary operation. A pituitary oncocytoma with randomly scattered S-100 immunoreactive cells was found upon histologic examination of the nodular tissue curettaged from the internal wall of the cyst. These results suggest that the pituitary adenoma was derived from folliculostellate cells included in the Rathke's cleft wall.