陥凹性病変を伴い深部大腸まで病変が認められたcap polyposisの1例

Cap Polyposis Consisted of Flat and Polypoid Lesions from the Rectum to the Ascending Colon, Report of a Case

要旨　患者は61歳，男性．頻回の水様性下痢を主訴に来院．下部消化管内視鏡検査で直腸から上行結腸にかけて半球状ないし平皿状の多発する隆起性病変とS状結腸に陥凹性病変を認めた．病変の頂部は発赤が強く一部には粘液の付着がみられたが介在粘膜は正常だった．病理組織像は陰窩の過伸展と粘膜面を覆う帽子（cap）状の炎症性肉芽組織を認め，特徴的な肉眼像と併せてcap polyposisと確診した．cap polyposisの報告例は近年増加しているが，いまだその病態は十分に解明されていない．また病変が直腸から深部大腸にまで及んだ報告例は極めて少なく貴重な症例と考え報告した．

　We report a patient with cap polyposis, which showed a unique endoscopic appearance and total involvement of the large intestine. A 61-year-old man was admitted with chronic diarrhea. According to both colonoscopic and radiographic findings, the lesions demonstrated both atypical and typical lesions of cap polyposis, that is, eroded and flat reddened lesions with irregular margins from the rectum to the sigmoid colon, eroded and sessile polypoid lesions from the sigmoid colon to the ascending colon, respectively. By histopathological investigation of biopsied specimens taken from the flat lesions and endoscopically resected specimens of the polyps, it was found that the lesions showed common histological characteristics that were compatible with those of cap polyposis. In conclusion, this case was atypical but unique, because the endoscopic and radiological findings showed flat eroded reddened lesions as well as typical cap polyps and because the polyps extended into the proximal part of the large intestine. It is suggested that the present case could be one of the various manifestations of cap polyposis. There are no previous reports describing these atypical lesions of cap polyposis. A greater variety of cases needs to be accumulated in order to clarify the pathogenisis of cap polyposis.