粘膜下腫瘍様の形態を示した消化管癌の鑑別診断

Differential Diagnosis of Gastrointestinal Cancer Mimicking Submucosal Tumor

要旨　粘膜下腫瘍（SMT）様の形態を示した消化管癌の鑑別診断について解説した．SMT様の形態をとる食道癌の多くは特殊組織型である．胃癌ではリンパ球浸潤の強い（lymphoid stroma）癌や粘液癌，大腸癌ではnon-polypoid growthを示すもの，粘液癌が多い．SMT様癌と鑑別が必要な非上皮性腫瘍は悪性リンパ腫，カルチノイド腫瘍，GISTを含む間葉系腫瘍，転移性癌である．また，部位別にみると食道では顆粒細胞腫，胃では迷入膵，異所性胃粘膜，inflammatory fibroid polyp，大腸では直腸粘膜脱症候群や脂肪腫である．いずれもヨード染色や色素撒布法を併用しわずかな上皮性変化を捉えることが重要である．SMT様癌を疑った場合は，経過観察は許されないので，確実に組織診断を行う必要がある．

　We reviewed the differential diagnosis of gastrointestinal cancer resembling submucosal tumor (SMT). Histologically, such tumors included particular histological types in esophageal carcinoma, i.e. basaloid squamous carcinoma, adenocarcinoma, adenosquamous carcinoma, mucoepidermoid carcinoma, adenoid cystic carcinoma and so on. In gastric carcinoma, they included carcinoma with lymphoid stroma and mucinous adenocarcinoma. In colorectal carcinoma, they included non-polypoid growth carcinoma and mucinous adenocarcinoma. Non-epithelial tumors, which commonly needed to be discriminated from SMT-like carcinoma, were malignant lymphoma, carcinoid tumor, mesenchymal tumor including gastrointestinal stromal tumor and metastatic tumor. Physicians have to make a correct diagnosis for SMT-like carcinoma by using the dye spraying method because most of them are carcinomas that have already invaded the sites of their location. Fine needle aspiration cytology is useful for correct histological diagnosis of these tumors.

　1) Third Department of Internal Medicine, Asahikawa Medical College, Asahikawa, Japan