Colorectal cancer implant in an external hemorrhoidal skin tag.

External hemorrhoidal skin tags are generally benign. Colorectal cancer metastases to the squamous epithelium of perianal skin tags without other evidence of disseminated disease is a very rare finding. We present the case of a 61-year-old man with metastasis to an external hemorrhoidal skin tag from a midrectal primary adenocarcinoma. This case report highlights the importance of close examination of the anus during surgical planning for colorectal cancers. Abnormal findings of the perianal skin suggesting an implant or metastatic disease warrant biopsy, as distal spread and seeding can occur. In our patient, this finding appropriately changed surgical management.