A case of Rathke's cleft cyst within a pituitary adenoma presenting with acromegaly--do "transitional cell tumors of the pituitary gland" really exist?

A case of multiple large Rathke's cleft cyst within a pituitary adenoma presenting with acromegaly is reported. Rathke's cleft cyst within a pituitary adenoma is rare condition, and this is the first report of such a case presenting with acromegaly. An electron microscopic and an immunohistochemical analysis proved that the cyst within the pituitary adenoma of this case differs from cysts found in the embryonic stage of the pituitary gland.