Purpose: Anorectal fistulas are commonly associated with Crohn's disease. Carcinoma arising in an anal fistula in the absence of Crohn's disease occurs rarely. Carcinoma arising in an anorectal fistula of Crohn's disease is likewise rare and is the subject of this article.
Methods: We have seen eight cases in seven patients. Four of these were squamous carcinoma and three were adenocarcinoma. Details of these seven patients are presented.
Results: Two deaths in the four patients with squamous carcinoma and one in the two patients with adenocarcinoma with adequate follow-up suggest a poorer prognosis in both types of malignancy than when these lesions occur without Crohn's disease.
Conclusion: Carcinoma does arise in the midst of the anorectal fistulas and abscesses of Crohn's disease. Carcinoma arising in a Crohn's disease fistula can be very difficult to diagnose. Examination may be limited by pain, stricture, or induration of the perianal and perineal tissues. Examination under anesthesia can also overlook the lesion. Diagnostic examination under anesthesia yields increases with biopsies or curettage of the fistulous tracts.