Primary and secondary adenocarcinomas associated with anal fistulae.

Purpose: The purpose of this study was to evaluate the clinical features, pathology, and etiology of adenocarcinoma in patients with anal fistulae.

Methods: We identified seven patients diagnosed with adenocarcinoma associated with anal fistulae from a retrospective chart review.

Results: Five patients were diagnosed with primary adenocarcinoma associated with anal fistulae. Two patients were diagnosed with secondary adenocarcinoma associated with anal fistulae originating from rectal cancer on the proximal side. The primary adenocarcinomas included cancers arising from long-standing anal fistulae fulfilling established diagnostic criteria in two patients, and cancer arising from short-duration anal fistulae in three patients. Excision of the fistula was performed based on the initial diagnosis of the anal fistula for all five patients. Increased suspicion of cancer was due to the existence of gelatinous material in the anal fistula in three patients and induration in the resected specimens in two patients. The etiologies of the secondary adenocarcinomas associated with anal fistulae included implantation in the anal fistula from rectal cancer and fistula formation originating due to the progression of rectal cancer.

Conclusion: Anal fistulae are commonly seen in the coloproctology clinic, but special attention to similar conditions associated with malignant disease is needed.