10年以上の経過で粘膜脱症候群からcap polyposisへの移行を観察できた1症例

Cap Polyposis from Mucosal Prolapse Syndrome Observed Over a 10-year Follow-up Period, Report of a Case

要旨　64歳，女性．粘液性下痢，下腹部痛を主訴に来院した．注腸X線検査で，直腸に狭窄があり，その上部の腸管は攣縮していた．大腸内視鏡検査で，横走する粘膜ひだの上に浅い潰瘍を認め，その部を先端として粘膜脱の所見が観察された．癒着した卵巣を狭窄・固定点としたS状結腸のMPSと診断し，自覚症状が消退しないため，1991年6月13日に直腸，S状結腸切除術を施行した．切除標本で肥厚した粘膜ひだを認め，所々がポリープ状に隆起していた．隆起部分は，腺筋症，炎症性細胞浸潤を伴う延長した腺管と脈管に富み，浮腫状の挙上した粘膜下層からなり，病理組織診断は粘膜脱症候群であった．その後，症状は再燃し，吻合部を切除し下行結腸に人工肛門を造設した．しかし，その後も，残された直腸よりの粘液便と人工肛門より上部の腹痛も持続していた．約10年後の1999年11月のX線，内視鏡検査で横行結腸に頂上に白苔を持つポリープが多発していた．cap polyposisと診断した．ポリペクトミー標本でポリープは腺筋症を伴う延長した腺管からなり，表層には粘液で囊胞状に拡張した腺管があり，表面には粘液成分が付着していた．今日，cap polyposisは粘膜脱症候群の病態のもとに生ずると考えられている．この症例は経過観察の中で，このことを画像と病理組織像から証明した症例である．

　A 64-year-old woman presented, in June 1990, with persistent mucous diarrhea and lower abdominal pain. Barium enema revealed an area of stenosis in the upper part of the rectum and the next rectosigmoid colon was spastic. Colonoscopy showed shallow ulcers on the transverse mucosal folds in the rectum and the prolapsing of the inner mucosa from the stenotic, fixed point. Mucosal prolapse syndrome (MPS) in the sigmoid colon due to adherent ovaries was diagnosed and, because of intractable symptoms, low anterior rectosigmoid-resection was performed on June 13,1991. The resected specimen showed hypertrophic transverse mucosal folds with flat polypoid lesions. The polypoid lesions were composed of elongated glands with fibromusculosis, inflammatory cells infiltration and the submucosal layer was elevated with rich vascular components. MPS was the pathological diagnosis.

　Unfortunately the patient's symptoms recurred within a short time and resection of the anastomosis and colostomy in the descending colon was carried out. However, the symptoms with mucous discharge in the remnant rectum and the pain in the upper abdomen persisted for a long time.

　About 10 years after the first operation, barium enema, in November 1999, showed many polypoid lesions on the apices of the transverse mucosal folds and their surface was covered by ‘cap’ with whitish mucous exudates. Polypectomy specimens showed findings comparable to cap polyps.

　The condition of this patient was diagnosed as a cap polyposis (CP).

　In this case, the course of MPS to CP was observed and the etiological factors of both clinical entites were thought to be similar and connected.