癌以外の肛門部の悪性腫瘍―メラノーマ，Paget病，Bowen病

Neoplasms Rarely Found in the Anal Area―Melanoma, Paget's Disease and Bowen's Disease

要旨　肛門部の悪性腫瘍としては，腺癌もしくは扁平上皮癌が主なものであるが，その他の悪性腫瘍としては，メラノーマ，Paget病，Bowen病がある．いずれも体表の皮膚のどこにでも発生しうるものであるが，肛門部にもまれにみられる．メラノーマはやや女性に多く，平均年齢は60～70歳，Paget病は男女ほぼ同数で，平均年齢は70歳前後，Bowen病は女性に多く，平均年齢は50歳前後とやや若い．メラノーマは黒色の隆起性腫瘍として発見されることが多いが，Paget病，Bowen病のいずれも湿疹や苔癬などの皮膚科疾患様の外見を示すことが多い．診断はいずれも生検により，組織学的に行われる．治療は，メラノーマは腹会陰式直腸切断術，Paget病，Bowen病は広範囲切除術が行われることが多い．予後はメラノーマでは特に不良で，5年生存率は，10％前後に過ぎない．Paget病，Bowen病は比較的予後良好である．

　The majority of anal neoplasms are adenocarcinoma and squamous cell carcinomas. Rare cases of these anal lesions are melanoma, Paget's disease and Bowen's disease. Melanoma, Paget's disease and Bowen's disease can occur in any skin location, but are rarely found in the anal area. Melanoma patients are more frequently women, and the average of age is between 60 and 70. In Paget's disease, patients, the average age is close to 70, and the desease is equally distributed among males and females. In Bowen's disease, women are affected more frequently than men and the average age is about 50 years old. Melanomas are mainly found as black elevated tumors. The appearance of Paget's disease and Bowen's disease is analogous to that of eczema or lichen. They are all diagnosed by biopsy and microscopic examination. Melanomas are mainly treated by abdomio-perineal resection. The treatment of Paget's disease and Bowen's disease is mostly a wide local excision. In melanomas, prognosis is very poor and five-year survival rate is only about 10％. In Paget's disease and Bowen's disease, prognosis is rather good.