1)上部消化管

Diagnostic Strategies for Submucosal Tumor of the Upper GI Tract

要旨　消化管粘膜下腫瘍は間葉系腫瘍や脂肪腫，嚢胞，カルチノイド腫瘍など多彩であるが，食道・胃粘膜下腫瘍の多くは間葉系腫瘍である．食道は平滑筋腫，胃はGISTが多い．粘膜下腫瘍は腺腫や癌と異なり正常な粘膜で被覆されていることから，組織診断に基づく治療方針を立てにくいという特徴がある．したがって，画像診断の組み合わせにより，ある程度診断を絞り込んで方針を決定する．さらに必要に応じて，組織診断を得る目的で，超音波内視鏡ガイド下の穿刺生検を慎重に実施する．良性もしくは低悪性度の腫瘍が多いことから，小さい腫瘍は外来で経過観察が続けられることも少なくないが，間葉系腫瘍の生物学的特性はいまだ不明な点も多く，臨床的対応については慎重であるべきと考える．

　Gastrointestinal submucosal tumor (SMT) includes a variety of tumors such as gastrointestinal mesenchymal tumor, lipoma, cyst, ectopic pancreas, carcinoid tumor, and so on. The majority of esophageal and gastric SMTs are mesenchymal tumors ; benign smooth muscle tumors in the esophagus and GIST in the stomach. Submucosal tumors are covered with a normal mucosal layer, so the decision about the most siutable therapeutic strategy based on the histopathological diagnosis of biopsy specimens is sometimes difficult. The combination of findings of several diagnostic modalities is a useful approach to reach a proper diagnosis of the tumor. EUS-guided fine needle aspiration biopsy is a useful tool for taking the tumor sample for histological diagnosis. Patients who have a small-sized mesenchymal tumor in the GI tract can be followed up in the outpatient clinic. Even in such cases, we should follow them up with periodical checkups, because of the ambiguity of the biological characteristics of mesenchymal tumors, especially GIST.

　1) Department of Surgery, Keio University School of Medicine, Tokyo