消化管粘膜下腫瘍の病理

Pathology of gastrointestinal submucosal tumors

要旨

消化管粘膜下腫瘍様の形態を示す上皮性病変は腫瘍，異所性組織，過形成・過誤腫が含まれ，非上皮性腫瘍は消化管の場所を問わず発生しうる。粘膜下腫瘍様の形態を示す病変は，食道では平滑筋腫，顆粒細胞腫などの非上皮性腫瘍が多い。胃はgastrointestinal stromal tumorが高頻度で，神経内分泌腫瘍や異所性組織もみられる。小腸はリンパ管腫が多い。大腸は直腸原発の神経内分泌腫瘍の頻度が高く，脂肪腫など非上皮性腫瘍もみられる。近年はEUS-FNAが消化管粘膜下腫瘍の病理診断に用いられている。生検検体で病理診断を行う場合は，上皮性か非上皮性か，発生臓器，病変の主座を考慮し，粘膜生検やEUS-FNAなど，病理診断が行いやすい検体採取方法を選択する必要がある。

　Gastrointestinal epithelial lesions with a submucosal tumor-like appearance include tumors, ectopic tissue, hyperplasia, and hamartomas, whereas non-epithelial tumors can occur anywhere in the gastrointestinal tract. Submucosal tumor-like lesions of the esophagus are often non-epithelial tumors such as leiomyomas and granular cell tumors. In the stomach, gastrointestinal stromal tumors (GISTs) are frequent, and neuroendocrine tumors (NETs) and ectopic tissues are also observed. Lymphangiomas are common in the small intestine. In the large intestine, NETs of the rectum are more frequent, and non-epithelial tumors such as lipomas are also observed. Recently, endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) has been used for the pathological diagnosis of gastrointestinal submucosal tumors. When pathological diagnosis is performed on biopsy specimens such as mucosal biopsies and EUS-FNA, the most pathologically accurate specimen sampling method must be selected, taking into consideration whether the lesion is epithelial or non-epithelial, the organ involved, and the location of the occupied lesion.