直腸肛門部悪性黒色腫の1例

Anorectal Malignant Melanoma, Report of a Case

要旨　症例は70歳代，女性．約1年前から肛門より脱出する腫瘤を自覚していたため当科を受診した．肛門直腸部に4cm大の口側に白苔を伴う，表面平滑な黒褐色から黒色調の粗大結節を有する有茎性腫瘤があり，腫瘤周囲および肛門管から肛門周囲に進展する黒色斑を認めた．生検で悪性黒色腫と診断した．診断には透明フード装着による観察が有用であり，超音波内視鏡，拡大内視鏡でも特異的所見を示した．画像検査上明らかな転移巣を認めなかったため，D2リンパ節郭清を伴う腹会陰式直腸切断術を行った．腫瘍浸潤は上皮下から粘膜下層までであり，リンパ節転移を認めなかった．

　A seventy something woman presented a mass protruding from her anus for about one year. A 4 cm-sized, black-to-blackish-brown, lobulated, pedunculated mass with white coating was identified in the anorectal region. Blackish pigmentation was observed from the tumor to the anal skin. A cap-fitted colonoscope was used for close observation. EUS and magnifying endoscopy revealed specific findings. The biopsy specimen showed malignant melanoma. As no obvious metastatic lesions were noted, abdominoperineal resection with D2 lymph nodes dissection was performed. Histopathologically, melanoma cells were shown to have invaded from the subepithelium to the submucosa with no lymph node metastasis.