Dedifferentiation and invasive growth of an eosinophil pituitary adenoma.

This report concerns the course of an eosinophil pituitary adenoma in an acromegalic female (16 years of age when first symptoms appeared) over a period of ten years. The case was complicated by craniocerebral trauma and CSF rhinorrhoea. After several operations, dedifferentiation, and invasive growth into the orbit and the petrous bone were observed with walling in of the VIIIth cranial nerve. The possible causes of the dedifferentiation of the adenoma are discussed.