Anal Metastasis Originating from Colorectal Cancer: Report of Two Cases

Abstract

Anal metastasis from colorectal cancer rarely occurs, but it severely impairs the patient's quality of life, often requiring wide resection including the anal sphincter with permanent colostomy. This lesion can be misdiagnosed as a perianal fistula or an abscess, and it can be overlooked at the time of surgery because it is not included in the routine surgical extent of low anterior resection. We report two rare cases of anal metastasis from colorectal cancer. In both cases, perianal nodules with an internal solid portion were detected on preoperative rectal magnetic resonance imaging and additional local excisions of the anal lesions were performed during the process of treatment. Anal metastasis was pathologically confirmed by histology and immunohistochemical staining.

Keywords

• colorectal neoplasms
• anus neoplasms
• anus diseases
• rectal fistula
• adenocarcinoma