原発性甲状腺機能低下症に合併した下垂体腺腫と過形成

A Case Of Pituitary Adenoma and Hyperplasia with Primary Hypothyroidism

I．はじめに

　原発性甲状腺機能低下症に下垂体腫瘤が合併することはよく知られている．Yamadaら^18）はX線学的に計測して約80％の症例でトルコ鞍の拡大を認めるとし，その大きさは血中のT4，T3値に反比例しTSH値にほぼ比例すると報告している．その治療方針として，甲状腺ホルモンの補充療法下に下垂体腫瘤の経過観察を行うことが一般的である．

　今回，われわれは高プロラクチン血症を呈しCT上にてトルコ鞍内から鞍上部にかけて均一に増強されるmassを認めた症例を経験した．下垂体腺腫の診断のもとに，経蝶形骨洞的に腫瘍摘出術を行った．しかし術後に原発性甲状腺機能低下症が判明し，ホルモン補充療法を行った．本例の術中所見及び組織学的所見よりpitui—tary adenomaとhyperplasiaが共存した症例と考えられたのでここに報告する．

Abstract

A 23 year-old woman was admitted to our hospital, complaining of sterility and obesity. Her serum TSH and Prolactin were abnormally high, and her serum T3, T9 were low. Contrast-enhanced computerized tomo-graphic (CT) scan revealed a round mass in the sellaand suprasellar region. A transsphenoidal operation was then performed. The intrasellar mass was corn-posed of a soft liquid-like part and a solid part. Only the soft liquid-like part of the mass was removed.

Histological examination showed the typical appea-rance of chromophobe adenoma, Reticulin stain of the specimen revealed no reticular network. The remnant of the mass was considered to be hyperplasia because the size of the mass decreased on serial CTscan after thyroid hormonal replacement.

Sometimes it may be difficult to distinguish between hyperplasia and adenoma. The application of reticulin stains is considered to be useful for diffrentation be-tween hyperplasia and adenoma.