肛門管癌脳転移の1例

A Case Report of Brain Metastasis from Anal Canal Carcinoma

Ⅰ．はじめに

　転移性脳腫瘍は脳腫瘍の21%を占めており，脳神経外科的処置を必要とする一般的な疾患の1つである．脳腫瘍統計⁴⁾によると，転移性脳腫瘍の中で大腸癌が占める割合は5.7%と報告されており，この中で全大腸癌の0.7〜1.8%を占めると報告されている肛門管癌は，非常に稀と考えられる．肛門管癌は，腺癌，扁平上皮癌，腺扁平上皮癌，類基底細胞癌に分類され，欧米のガイドラインや治療成績の集積により化学放射線療法が主体となりつつあるが，遠隔転移を伴う症例の報告は非常に稀であり，確立された治療法はないとされている．

　今回われわれは，肛門管腺癌の脳転移例を経験し，外科的処置を含めた加療を行ったので報告する．

　A 55-year-old female with adenocarcinoma of anal canal（stage Ⅳ with lung, bone, and lymph node metastasis）underwent total pelvic exenteration surgery and chemotherapy. Chemotherapy was continued after the surgery. One month later, she presented to the emergency room with gait disorder and cognitive dysfunction. CT and MRI demonstrated metastatic brain tumor in the right cerebellar hemisphere. Craniotomy and CyberKnife surgery were performed. Histological examination revealed adenocarcinoma with atypical cells forming a papillary arrangement. She died 35 weeks after the surgery. Brain metastasis from anal carcinoma is very rare, but recent advances in chemotherapy are achieving favorable results of long-term survival, and this is likely to increase in the future. Early detection, early treatment, and combined therapy may improve the long-term outcome for patients.