A rare case of synchronous anal metastasis from sigmoid adenocarcinoma: case report and literature review.

INTRODUCTION

Anal metastasis from colorectal cancer is extremely rare, since most cases in the literature are associated with a history of anal disease, such as anal fistula, fissure, hemorrhoidectomy, and anastomotic injury.

CASE: Herein, we report the case of a 63-year-old male patient, who presented with synchronous anal metastasis from a sigmoid cancer in the absence of epithelial damage treated with trimodality therapy that consisted of neoadjuvant chemoradiotherapy followed by abdominoperineal resection.

DISCUSSION: True cutaneous metastases to the anal skin from colonic carcinomas are exceedingly uncommon and are likely underpinned by diverse mechanisms such as lymphatic dissemination, transperitoneal extension, direct extension, retrograde vascular dissemination, or systemic hematogenous spread. This pattern of metastasis is particularly observed in advanced tumor presentations.

CONCLUSION

This report guides clinicians to think about this rare type of metastasis. However, more clinical data is necessary to establish treatment and postoperative management plan for anal metastasis derived from colorectal cancer.