Granular cell tumor (choristoma) of the neurohypophysis: two cases and a review of the literature.

Primary tumors of the neurohypophysis and infundibulum are extremely rare. Two types are known: glioma, also known as pilocytic astrocytoma or pituicytoma; and granular cell tumor, also known as choristoma, myoblastoma, or granular cell myoblastoma. Several authors [1-7] suggest that they are a fairly common incidental finding at autopsy, but reports of masses large enough to cause symptoms are few; the last report in the radiologic literature was in 1956 [3]. We are unaware of previous descriptions of the MR appearance of granular cell tumors. We present two cases of this rare neoplasm and a review of the literature.