# Late-Onset Isolated Drain Site Metastasis in Colorectal Cancer Managed by a Multidisciplinary Approach

## TL;DR

A patient with colorectal cancer had a rare recurrence at a surgical drain site, managed successfully with surgery and no further treatment.

## Contribution

This case highlights a rare metastasis pattern in CRC, suggesting possible mechanisms like surgical seeding or tumor dormancy.

## Key findings

- A patient in remission from CRC developed an isolated recurrence at the surgical drain site two years post-treatment.
- Microsatellite instability status differed between the primary tumor and the recurrent lesion.
- Surgical resection of the recurrence achieved negative margins and long-term disease-free survival.

## Abstract

Colorectal cancer (CRC) is one of the most common cancers globally and a leading cause of cancer-related deaths. Over the past decade, our understanding of CRC has significantly evolved, particularly in the areas of genomic prognostication and targeted therapies. However, surgical management beyond the initial resection of the primary tumor remains an area of ongoing discussion and research.

We report a case of a 51-year-old man with metastatic CRC and liver metastases, treated with right hemicolectomy and chemotherapy, achieving complete remission. Two years later, he developed an isolated subcutaneous recurrence at the prior surgical drain site. Microsatellite instability status changed from primary to recurrent lesions. Surgical resection achieved negative margins, and the patient has since remained disease-free without additional therapy.

This rare presentation challenges traditional models of CRC metastasis and highlights the potential role of lymphatic dissemination, tumor dormancy, or surgical seeding.