直腸MALTリンパ腫の1例

Mucosa-associated Lymphoid Tissue (MALT) Type Lymphoma of the Rectum, Report of a Case

要旨　患者は72歳，女性．血便のため当院を受診した．注腸X線検査では直腸に約2cm大の粘膜下腫瘍があり，表面に小顆粒状のバリウム斑を認め，内視鏡検査では黄白色調の半球状の隆起性病変で頂上に斑状のびらんとわずかの出血を認めた．超音波内視鏡検査では内部エコーは充実性均一で，斑状の散在する点状高エコーを認めた．経肛門的腫瘍切除を行った切除標本の組織学的検索では，病巣は粘膜下層に主座があり，腫瘍内にはリンパ濾胞の残存が認められた．その濾胞間には小型から中型のcentrocyte-like cellの増殖が認められた．細胞増殖能は低く，低悪性度直腸MALTリンパ腫と診断された．直腸で粘膜下腫瘍をみた場合はMALTリンパ腫を念頭に置いた検索が必要であり，鑑別診断には超音波内視鏡が有用であると考えられた．

　A 72-year-old female visited to our hospital because of bloody stool. Barium enema x-ray examination and total colonoscopy revealed a submucosal tumor, measuring in 20 mm in the lower rectum. Endoscopic ultrasonography showed a circumscribed hypoechoic mass with several internal slight hyperechoic spots at the second and third layers of the rectal wall. Tumorectomy was performed. Histologically, the resected tissue had small to medium-sized centrocyte-like cells aggregations and reactive lymphoid follicles in the submucosa, so was diagnosed low-grade MALT lymphoma.

　We have to know the MALT lymphoma for differential diagnosis of the rectal submucosal tumor.