蝶形骨洞内に限局した異所性下垂体腺腫の1例

A Case of Ectopic Pituitary Adenoma Localized in the Sphenoid Sinus

I．はじめに

　異所性下垂体腺腫は稀な腫瘍であるが，蝶形骨洞内に限局したものは非常に少ない．今回われわれは，手術により蝶形骨洞内に限局した異所性下垂体腺腫と確認した症例を経験したので，神経放射線学的所見を主に，文献的考察を加え報告する．

Intrasphenoidal pituitary adenoma is relatively rare. Only 13 cases have been reported in the literature.We present a case of intrasphenoidal pituitary adenoma in a 74-year-old man. He had no endocrinologicalabnormalities. Skull tomograms revealed sellar floor erosion but showed no enlargement of the pituitaryfossa. Computed tomographic (CT) scan revealed an isodense mass showing no contrast enhancement inthe sphenoid sinus. The intrasphenoiclal tumor appeared slightly hypointense compared with normal brainon T1-weighted image, and showed less contrast enhancement after intravenous injection of Gd-DTPA onmagnetic resonance imaging (MRI).

Transsphenoidal pituitary microsurgery was performed, and all of the intrasphenoiclal tumor was remov-ed with the mucosa. The sellar floor was thin and easily breakable in parts. After removal of the sellarfloor the dura was opened, but no evidence of a pituitary tumor was shown. No connection between thepituitary gland and the sphenoidal tissue was found.

Microscopic examination of sections showed tumor cell nests in the sphenoidal mucosa. We think thisectopic pituitary adenoma occured through the migration of Rathke's pouch in the sphenoid sinus.