Ⅱa＋Ⅱc型の形態を呈した上行結腸原発早期悪性リンパ腫の1例

Early Malignant Lymphoma Mimicking Type Ⅱa＋Ⅱc Early Cancer of the Ascending Colon, Reort of a Case

要旨　患者は49歳，男性．検診で便潜血陽性を指摘され来院．注腸X線検査では上行結腸に扁平な隆起性病変を認め，大腸内視鏡検査では同部位にⅡa＋Ⅱc型の腫瘍が認められ，生検で悪性リンパ腫と診断された．理学的には表在のリンパ節腫大はなく，CTや超音波検査でも腹腔内リンパ節腫大や肝脾腫はみられなかった．上行結腸原発悪性リンパ腫の診断で右半結腸切除を施行した．摘出標本では上行結腸に15×12mm大のⅡa＋Ⅱc型の腫瘍を認め，組織学的には粘膜固有層，粘膜下層に浸潤したnon-Hodgkin's lymphoma，diffuse，mediurn-sized cell typeであった．免疫組織化学染色ではCD21，IgM，λで陽性を示し，B cell由来であった．大腸原発の早期悪性リンパ腫の形態について若干の考察を加えた．

　A 49-year-old man was admitted to our hospital for further evaluation of positive fecal occult blood noted an annual health check-up. Barium enema showed an elevated lesion in the ascending colon. Colonoscopic examination demonstrated a type Ⅱa＋Ⅱc-like lesion, whose biopsy specimen revealed malignant lymphoma. Neither lymphadenopathy of the entire body nor hepatosplenomegaly was detected by physical examination and imaging studies. A tentative diagnosis of primary malignant lymphoma of the ascending colon was made and the right hemicolectomy was performed. The resected specimen showed a type Ⅱa＋Ⅱc-like lesion, 15×12 mm in size. Histochemical examination revealed non-Hodgkin's lymphoma, diffuse medium-sized cell type. The tumor invasion was limited within the mucosal and submucosal layers. There was no metastatic lesion in the resected lymph nodes. Immunohistochemically, the surface of most tumor cells was positively stained with monoclonal antibody against CD 21, IgM and. λ. These results confirmed the diagnosis of primary malignant lymphoma of the ascending colon, originating from B cell. No chemotherapy was given. The patient has been doing well in the 11 months since operation without sign of recurrence.