Anal carcinoma occurring in Crohn's disease patients with chronic anal fistula.

: This paper reports six patients with perianal Crohn's disease (CD), who developed anal cancer in chronic anal fistulas. Tumors have been often diagnosed at an advanced stage and had a worse prognosis than cancers arising in the general population as tumor symptoms may mimic symptoms of CD, resulting in delay in diagnosis. Patients with perianal CD should undergo a careful surveillance program for ano-rectal carcinoma, including routine biopsy of any suspected lesion. When malignancy is found, an aggressive surgical approach and complementary therapy are mandatory.