術前検査で確診しえた十二指腸球部カルチノイド―somatostatinomaの1例

Duodenal Carcinoid (Somatostatinoma) Diagnosed by Endoscopic Biopsy and Hypersomatostatinemia, Report of a Case

要旨　術前に十二指腸ソマトスタチン産生腫瘍（somatostatinoma）と診断しえた極めてまれな1例を経験したので報告した．患者は59歳の男性で十二指腸前壁に径9mmのポリープを認め，頂部に陥凹とびらんがあり，生検でカルチノイドの診断を得た．また血清ソマトスタチンは高値（160pg/ml）でsomatostatinomaが疑われた。術後血清ソマトスタチンは正常化したことと，免疫組織化学で腫瘍内のソマトスタチン陽性を確認したことから本邦で4例目，術前に確診できたものでは第1例目の十二指腸somatostatinomaと考えられた．腫瘍は通常のカルチノイドと異なる腺管形成を呈する部分があり，浸潤は粘膜下組織まで及んでいた．

　A rare case of duodenal somatostatinoma, which was diagnosed by endoscopic biopsy and hypersomatostatinemia was reported.

　A 59-year-old man was under follow-up tests after a duodenal polyp. This polyp was located at the anterior wall of the duodenal cap, and was associated with a small erosion on the top (Figs. 2 and 3). Diagnosis as carcinoid tumor was made by endoscopic biopsy. Hypersomatostatinemia (160 pg/ml) was confirmed, and the diagnosis of somatostatinoma was made.

　The tumor, 8×7×4 mm in size (Fig. 4), was found after surgical operation. Microscopic examination revealed a carcinoid which showed a glandular pattern. Infiltration was limited to the submucosal layer (Figs. 5 and 6). Somatostatin was identified in the tumor cells by immunocytochemistry (Fig. 7). After the operation, serum Somatostatin level returned to normal limits (8.2 pg/ml).

　This is the fourth case of duodenal somatostatinoma (Table 2) and the first case of this tumor diagnosed before surgical operation, even reported in Japan.