回盲弁近傍の単純性潰瘍の病理

Pathomorphologic Study of Simple Ulcer in Ileocecal Region

　腸の単純性潰瘍（simple ulcer）とは，その原因（細菌，真菌，寄生虫，膠原病や，動脈硬化症など虚血性病変の起因となる基礎疾患，など）が明らかでなく，また潰瘍性大腸炎やクローン病とも異なり，肉眼的には円形ないし卵円形の下掘れで，打抜き様の深い潰瘍で（報告例の中には必ずしもこの肉眼形態でないものもある^1)3)12)），組織学的には非特異性炎症像を示す潰瘍を一般に指している．

　単純性潰瘍には多数の同義語がある．既知の原因による疾患や既知確立疾患と異なり，しかも，組織像が非特異的であるという意味で，単純性非特異性潰瘍（simple nonspecific ulcer），単発性を強調した，孤立性（非特異性）潰瘍（solitary nonspecific ulcer），臨床的にも急性症状を呈するとのことで，急性孤立性（単純性）潰瘍（acute solitary or acute simple ulcer），他にsolitary ulcerやnonspecific ulcerなどである．後述するように，この潰瘍は多発する傾向がある．また，原因の明らかな潰瘍でも治癒傾向が強くなると，非特異性炎所見を呈することはよくある．このような理由から，本稿では「単純性潰瘍」という用語を用いることとする．

　Simple ulcers of ileocecal region reported in the literature seem to be confused with other diseases, especially ulcers secondary to diverticulitis and ulcers of entero-Behçet's disease. In order to discriminate between them, we made a histopathologic comparative study, using eight cases of diverticular ulcer each accompanying multiple diverticula in the cecum and ascending colon, seven cases of complete or incomplete Behçet's disease and five cases of simple ulcer.

　All patients of diverticular ulcer complained of acute abdominal pain at the admission or in the past. The ulcers were round or oval with margin pulled down into their floor. The muscularis propria was penetratingly disrupted, being well preserved in its direction at the ulcer margin in most cases. The inflammatory infiltrate was fairly well demarcated in a shadow of diverticulum and, in its distribution, narrow in the muscularis propria and widest in the pericolic fat tissue. Therefore, on section, it made a form of an hourglass with a smaller head.

　Histologically, the infiltrate consisted of abundant neutrophils forming an acute abscess in the early stage, and of abundant plasma cells, neutrophils, lipophages, giant cells, lymphocytes and fibroblasts in the later stage.

　All patients of simple ulcer had a gradual onset of the disease. The ulcers were punched-out, round to oval with undermining margin. They were deep, Ul-Ⅳ, with disruption of muscularis propria near under destruction of muscularis mucosae. Microscopically the ulcers were entirely covered by a layer of neutrophils and necrotic tissue underlaid by a zone of vascular granulation tissue with predominant diffuse lymphocytic infiltration, and, in the serosal layer, by a cellular fibrous tissue though not prominent.

　Simple ulcers occurred on the ileocecal valve in all cases, where the ulcers were incurable, and were associated with daughter ulcers, Ul-Ⅱ to Ul-Ⅳ, in the ileum in four of five cases. In one recurrent case, ulcer occurred in the anastomotic site as well as in the ileum. Simple ulcers were seen in 65 per cent at the antimesenteric side, 31 per cent at the mesenteric and four per cent at the intermediate.

　Ulcers of entero-Behçet's disease were essentially the same to those of simple ulcers as regards to distribution, and macroscopic and microscopic appearance, but recurred in 57 per cent as compared to 20 per cent recurrence in the latter.

　It is quite possible to differentiate simple ulcer from diverticular ulcer histopathologically. However, differentiation of simple ulcer from ulcer of entero-Behçet's disease is morphologically impossible to our today knowledges. Until the time of fully explaining the difference between them, simple ulcer should be dealt with as a separate entity of disease.