[A case of prolactinoma in close association with Rathke's cleft cyst]

We report a case of Rathke's cleft cyst in pituitary tumor. A 31-year-old woman admitted to our hospital complained of visual disturbance, headache, amenorrhea and galactorrhea. Serum prolactin level was 3,060 ng/ml. By means of CT scan and MRI, we found suprasellar-extending tumor to have cystic component in the center of the tumor. Transsphenoidal surgery revealed grayish jelly-like content in the cyst. Histologically tumor cells were composed of chromophobic, basophilic and eosinophilic cells. The cyst wall in the pituitary adenoma was composed of ciliated or non-ciliated columnar epithelium intermingled with goblet cells, being similar to Rathke's cleft cyst. Except for the cells of the cyst wall, most of the tumor cells were immunoreactive for prolactin. As for intermediate filament, tumor cells in both solid and cystic portions showed positive immunoreactivity for cytokeratin and GFAP, and not for vimentin and neurofilament. These results suggest that the nature of the intracytoplasmic filament in the pituitary tumor with Rathke's cleft cyst may be not only keratin but also GFAP.