cap polyposisの1例

Cap Polyposis, Report of a Case

要旨　患者は67歳，女性．3年前から下腹部痛，粘液便あり．直腸に多発性隆起病変を認め，直腸粘膜脱症候群（MPS）を疑い経過観察していたところ，約1年後にS状結腸中部と上部にも新たに多発性隆起病変が出現していた．MPSとしては特異な病変の口側進展からcap polyposis（CP）を疑い，保存的治療を継続したが，症状は改善せず手術施行．切除標本でCPに特徴的な肉眼像（腸管の短軸方向の索状ひだの頂部に縦列する，表面発赤調の隆起病変で介在粘膜は正常）と病理組織像〔隆起表面粘膜の陰窩の過伸展と頂部に帽子（cap）状の炎症性肉芽組織の付着〕を認めCPと確診した．CPはMPSの類縁疾患と考えられているが，本邦ではまだ十分に認識されてなく，貴重な症例と考えられた．

　A 67-year-old woman was admitted to our hospital, complaining of lower abdominal pain and mucoid diarrhea over the last three years. Barium enema and colonoscopy showed circumferential polypoid lesions in the rectum, which were though to be suggestive of mucosal prolapse syndrome (MPS). After about one year follow-up, in addition to the rectal lesions, multiple eroded polypoid lesions surrounded by normal or edematous mucosa appeared in the sigmoid colon. These findings, which were not compatible with MPS, led to srong suspicion of cap polyposis. The patient was treated with corticosteroid and sulfasalazine suppository. However, her symptom worsened and rectosigmoid colectomy was performed. Macroscopic findings of the resected specimen showed multiple polypoid lesions on the apices of transverse mucosal folds separated by normal mucosa. Microscopic findings that the polypoid lesions were composed of elongated tortuous crypts and their surface were covered by ‘cap’ of fibrinopurulent exudate and inflammatory granulation tissue. From these pathological features, we diagnosed this case as cap polyposis. Cap polyposis is a extremely rare condition, which may be confused with other inflammatory bowel diseases such as MPS. We reviewed the literature about the clinical features of this disease.