蝶形骨洞内異所性下垂体腺腫の1例

A Case of Ectopic Pituitary Adenoma Occurring in the Sphenoid Sinus

Ⅰ．はじめに

　異所性下垂体腺腫はトルコ鞍内正常下垂体前葉と異なる起源をもつ比較的稀な腫瘍であり，1909年Erdheimらによって最初のケースが報告されて以後⁴⁾，MRIの普及に伴い，鼻腔^1,12,22)，鼻咽頭^1,24)，蝶形骨洞^{2,5,9,10,15,17,19,29,34,37)}，斜台^3,36)，海綿静脈洞^8,14,20,28)，蝶形骨小翼部⁶⁾，錐体骨²⁶⁾，鞍上部^{7,13,18,21,27,30,32,35)}，下垂体茎部²³⁾，脚間層³¹⁾，第三脳室内発生例¹⁶⁾などの報告が散見される．今回われわれは，蝶形骨洞内に発生した非機能性異所性下垂体腺腫の1例を経験した．画像上の特徴，鑑別疾患など文献的考察を加えて報告する．

　Ectopic pituitary adenomas are relatively rare tumors. We present a case of ectopic pituitary adenoma occurring in the sphenoid sinus. A 63-year-old woman was referred to our hospital complaining of headache. She had no endocrinological abnormalities. Magnetic resonance imaging showed a tumor in the sphenoid sinus,adjacent to the sellar floor and appearing as a low-signal on T1-weighetd image and a high signal on T2-weighted image. No connection between the normal pituitary gland and tumor was observed. Using an endonasal-transsphenoidal approach assisted with neuro-endoscopy,we performed total removal of the tumor. No connection between the normal pituitary gland and the tumor was found. Histopathological analysis showed a pituitary adenoma. As demonstrated by our case report,differential diagnosis of a tumor occurring in the sphenoid sinus must include consideration of the existence of an ectopic pituitary adenoma.