大腸憩室病の最近の考え方―特に病理，病理発生を中心に

Pathology and Pathogenesis of Diverticular Disease of the Colon

　近年，大腸疾患に対する興味の高まりとともに，大腸憩室病の発見頻度も上昇する傾向にある，大腸憩室病に関する総説的論文は数々あるが，それらの内容を総合すると大腸憩室病の最近の考え方を以下のように要約できよう．

　種々の原因によって，大腸固有筋層のmortor activityが上昇し，筋層肥厚などのmuscle abnoromalityが生じるとともに腸管内の圧上昇がもたらされる．この圧上昇のために腸管壁のweak spots，主として血管侵入部において粘膜の腸壁外へのherniationが生じる，これが憩室であり，diverticulitis，peridiverticulitisなどはこの憩室に派生的に発生する合併症の1つである．

　このような考え方が生まれるに至るには，X線学的研究，組織学的研究，生理学的研究の積み重ねが必要であった．ここにこれらの研究の足跡をたどりつつ，大腸憩室病の病理，病態を浮き彫りにしたいと思う．

　Pathology and pathophysiology of diverticular disease is reviewed and the new look on pathogenesis is introduced.

　There are four types of diverticular disease of the colon (Morson), 1) diverticulosis of the sigmoid colon with muscle abnormality, 2) diverticulosis of a part or the whole of the colon without muscle abnormality, 3) diverticulum of the cecum or ascending colon, 4) right sided diverticulosis. The former three types are very common in Caucasian people and the last type is rare in Caucasians but is the commonest type in certain Oriental races including Japanese. Pathology and pathophysiology of diverticulosis of the sigmoid colon with muscle abnormality has been well documented in the world literature. It is suggested that diverticular disease of this type is basically a disorder of muscle function. The increase in the tone of the longitudinal muscle, particularly the teniae coli, and the contractions of the circular muscle cause muscle thickening and intraluminal high pressure which facilitates mucosal herniation at the weakest spots where the vessels penetrate the bowel wall. The inflammation in diverticular disease is purely a complication of diverticulosis.

　Pathogenesis of right sided diverticulosis is unkown. Much more information is required about the incidence and pathology of the different types of diverticular disease in different races and geographical areas, as it is likely that such knowledge will lead to clarification of the environmental and predisposing factors involved.