トルコ鞍内に限局し，手術単独で良好な結果が得られたTSH産生下垂体腺腫の2例

Intrasellar Small TSH Secreting Pituitary Adenomas,2 Case Reports

Ⅰ．はじめに

　Thyroid stimulating hormone（TSH）産生下垂体腺腫は，下垂体腺腫全体の内1％を占めるに過ぎない稀な腫瘍である^1,4,7,14)．臨床的にはinappropriate secretion of TSH（SITSH）を来さずにいわゆる非機能性腺腫として経過したり¹³⁾，Graves 病の診断のもと抗甲状腺剤投与や甲状腺に対する放射線療法，甲状腺腫切除等不適切な治療を余儀なくされ，発見時には大きな腫瘍径を持つ浸潤性腫瘍となり治療に難渋することも少なくない．一方，本腫瘍は，間質の線維化が強い硬い腫瘍としての特徴を備えている．今回われわれは，トルコ鞍内に限局し比較的小さな状態で発見，手術を施行したTSH産生下垂体腺腫の2例を経験した．浸潤性の強い腫瘍に対して困難な手術を想定していたが，これに反して手術は比較的短時間で，肉眼的全摘出が可能であった．手術所見と内分泌，病理組織学的所見との対比につき，文献的考察を加え報告する．

　Thyroid-stimulating hormone (TSH)-secreting pituitary adenoma accounts for 1% of pituitary adenoma and often manifests as invasive macroadenoma. If the TSH value is not high enough to cause clinical symptoms presenting as inappropriate secretion of TSH, the tumor may be missed or misdiagnosed as Graves disease. Some of these patients receive inadequate treatment with the antithyroid agent, radioiodine treatment, and thyroidectomy. This tumor is also known as a tough and firm tumor because of the significant interstitial fibrosis. We report two cases of TSH-secreting pituitary adenomas which were comparatively small. Although a tough and difficult operation was expected, actual tumor dissection was easy and gross total removal was achieved within less than 3 hours. We discuss the relationship between the intraoperative findings and histopathology, as well as the ultrastructure and endocrinology.