びまん浸潤型を呈した直腸原発悪性リンパ腫の1例

Primary Malignant Lymphoma of Diffusely Infiltrating Form in the Rectum, Report of a Case

要旨　患者は61歳，男性で下痢，粘血便を主訴に来院した．大腸内視鏡検査で直腸に広範に及ぶ脳回様の腫大した粘膜ひだとその間に多発の小潰瘍やアフタ様びらんを認めた．鉗子生検で病変の確診が得られず，経肛門的直腸粘膜部分切除の生検で悪性リンパ腫と診断され，直腸切断術を施行した．肉眼形態はびまん浸潤型を呈し，深達度は主としてsmを広範に浸潤していたが，一部でpmに小浸潤していた．直腸原発性悪性リンパ腫は比較的まれで1987年までに60数例の報告をみるが，そのほとんどが腫瘤，潰瘍を形成する限局型である．本症例は胃悪性リンパ腫における巨大皺襞型に当たるびまん型直腸悪性リンパ腫と考えられ，特にまれと考え報告した．

　A 61-year-old man was admitted to our hospital with a three-week history of diarrhea and mucohemorrhagic stool. Endoscopic examination revealed multiple ulcer or aphthous lesions in diffusely thickened rugous folds in the rectum. Surrounding mucosa appeared to lack inflammation and translucency of vascular networks. No definitive diagnosis was made by an endoscopic biopsy. The diagnosis of malignant lymphoma, however, was attained by microscopic examination of excisional specimens of the rectum by transanal approach. HistologicaIly, the tumor spreaded mainly in the tela submucosa and partly into the tunica muscularis propria, and thus was diagnosed as diffusely infiltrating form of rectal malignant lymphoma.

　Primary malignant lymphoma of the rectum is a rare disease, and about 60 cases were reported in Japan until 1987.

　The reported cases so far were mostly circumscribed with ulcer or polypoid lesion. The cases of diffusely infiltrating form were much less frequently seen. We reported here a case of rectal malignant lymphoma of diffusely infiltrating form.