# Perianal Mucinous Adenocarcinoma: A Case of Recurrent Anal Fistula

## TL;DR

A rare case of perianal mucinous adenocarcinoma was diagnosed in a patient initially suspected of having Crohn's disease.

## Contribution

Highlights the importance of multidisciplinary assessment in diagnosing rare malignancies masquerading as benign conditions.

## Key findings

- Perianal mucinous adenocarcinoma can present as a recurrent anal fistula.
- Malignant transformation in anal fistulas is rare but must be considered in differential diagnosis.
- Multidisciplinary evaluation is crucial for accurate diagnosis and timely treatment.

## Abstract

An anal fistula is a fairly common clinical condition, with a very low incidence of malignant transformation. Mucinous adenocarcinoma is a subtype of adenocarcinoma, and its occurrence within perianal fistula tracts is quite rare. This case report describes a 54-year-old male patient with recurrent anal fistula, initially suspected of Crohn's disease (CD), and ultimately diagnosed with perianal mucinous adenocarcinoma. After our joint internal medicine, surgery, and imaging reassessment, the diagnosis was confirmed. Anal fistula is usually considered a benign lesion, but it may also be associated with other diseases. Due to overlapping symptoms of related diseases, the investigation of malignant lesions is often overlooked. This case report emphasizes the importance of timely referral and multidisciplinary management for disease diagnosis and early treatment.