同一細胞よりGHとTSHの分泌をみた下垂体腺腫の1例—二重免疫染色による検討

A Case of Pituitary Adenoma with Simultaneous Secretion of TSH and GH Detected by Double Immunostaining Method

　TSH産生下垂体腺腫は極めて稀な腺腫の一つであり，他のホルモン分泌を合併することが多いという特徴を持つ。GH分泌を伴ったTSH産生下垂体腺腫の1症例を経験し，二重免疫染色を用いて光学顕微鏡下でこれらのホルモンが同一細胞より分泌されていることを証明したので報告する。症例は甲状腺機能亢進症状を有する59歳の男性で，血中甲状腺ホルモン値が高いにもかかわらず，血中TSH値は抑制されず高値を呈した。CTおよびMRIでトルコ鞍内に腫瘍陰影が認められたため，原発性TSH産生下垂体腺腫と診断され，経蝶形骨洞法により腺腫が全摘出された。組織学的には嫌色素性腺腫であり，免疫染色ではTSHとGHが陽性を呈した。Avidin-biotin-peroxidase complex（ABC）法とimmunogold-silver法を用いた二重免疫染色では，GHの染色の上にTSHが銀粒子の析出として描出され，GHとTSHは同一細胞より分泌されていることが示された。

A rare case of simultaneous hypersecretion of thyroid stimulating hormone (TSH) and growth hormone (GH) in a pituitary adenoma is reported. A 59-year-old male complaining of general fatigue, dyspnea on exertion and finger tremor was admitted. Examination on admission, he revealed with hyperthyroidism and hypersecretion of TSH and thyroid hormones. Administration of TRH did not further increase serum TSH level, and admini-stration of T3 also had no effect on TSH secretion. CT scan showed a pituitary macroadenoma 13mm in diame-ter. MRI demonstrated a homogenously hypointense mass with Gd-DTPA enhancement in the left side of the sella turcica. The entire chromophobic adenoma was removed by trans-sphenoidal surgery. Immunostaining of the specimen showed that the cytoplasm of the adenoma cells was positive for both TSH and GH. Double immunostaining using avidin-biotin-peroxidase complex (ABC) method and immunogold silver staining (IGSS) method, showed that the adenoma cells had been secreting both GH and TSH at the same time. After the adenomectomy, the hyperthyroidism disappeared, and all altered indicators of pituitary function returned to normal.