臨床からみたcap polyposis―報告例20例と自験例5例の検討

Clinical Features of Cap Polyposis

要旨　cap polyposisは近年注目されている比較的まれな大腸の炎症性疾患である．原因は不明であるが，大腸の運動機能異常に伴う慢性的な機械的刺激説が有力で，直腸粘膜脱症候群との異同が問題になる．報告例と自験例の計25例について検討した．年齢は20～76歳で好発年齢はなく，女性に多い．症状は粘液下痢ないし粘血便が多い．血液検査所見ではしばしば低蛋白血症がみられ，炎症反応は通常陰性である．内視鏡所見は，典型例では直腸からS状結腸にかけて多発性広基性ポリープを認め，病変の表面には発赤と粘液の付着がみられる．病変の周囲にしばしば小白斑が観察され，介在粘膜はほぼ正常である．一方，病変が右側結腸まで存在したり，発症初期や緩解期には典型像を示さない場合がある．治療は一般に5‐アミノサルチル酸製剤やステロイドは無効で，metronidazoleが有効な症例がある．外科的切除術や内視鏡治療を行っても短期間に再発する場合が多い．

　Cap polyposis is an inflammatory bowel disease, which was firstly reported by Williams et al. in 1985. This rare disease has characteristic clinical, endoscopic and pathological features. The etiology of this disease is still unknown, but chronic mechanical stimulation by abnormal colonic motility may play an important role in its pathogenesis. We studied 20 reported cases and our 5 cases. The patients' ages ranged from 20 to 76 years, with an average of 48.0. The sex ratio was 6 men to 19 women. The most common symptoms were mucous diarrhea or mucous bloody stool. Laboratory data showed hypoproteinemia due to protein loss from the lesions in most cases, and markers of inflammation such as CRP and ESR were usually normal. Typical endoscopic findings revealed multiple sessile inflammatory polyps, which were reddish and attached by mucous in the rectum and the sigmoid colon. Multiple white specks were often observed surrounding the lesions, but the intervening mucoua was generally normal. On the other hand, these typical endoscopic findings were sometimes not recognized in the initial or improved phase. 5-aminosalicylic acid agents and steroid hormone were usually not effecitive, but metronidazole was effective in some cases. Surgical resection and endoscopic therapy reduced symptoms temporally, but recurrences were recognized within 12 months in many cases. Treatment by avoidance of intraluminal trauma such as straining at defecation was successful in some cases.