直腸MALTリンパ腫—鑑別のポイントを中心に

Rectal Mucosa-associated Lymphoid Tissue Lymphoma：Focusing on Differential Diagnosis

要旨●直腸MALTリンパ腫は悪性リンパ腫の消化管原発性で，びまん性大細胞型B細胞リンパ腫（DLBCL）と同様に多くみられる疾患である．直腸に発生する腸管非上皮性腫瘍は鑑別疾患が多く，しばしば診断に難渋する．本稿では，直腸における非上皮性腫瘍の鑑別疾患を挙げ，またそれぞれの画像を提示しながら，病理組織学的所見，超音波内視鏡所見を含めて鑑別のポイントを中心に直腸MALTリンパ腫の診断アプローチを解説する．

　Rectal MALT（mucosa-associated lymphoid tissue）lymphoma is a primary malignant lymphoma of the gastrointestinal tract, and it is as common as diffuse large B cell lymphoma. Nonepithelial tumors of the rectum are often difficult to diagnose owing to numerous differential diseases. In this article, we aim to list the differential diseases of nonepithelial tumors of the rectum and present images for each of them. Moreover, we aim to explain the diagnostic approach for rectal MALT lymphoma by focusing on the points of differentiation, including histopathological findings and endoscopic ultrasonography.