[Crohn disease with unusual cutaneous expression].

Perianal fistula is a frequent complication of Crohn's disease. The diagnosis of the later may be difficult if cutaneous disease is dominant, and sometimes an important clinical challenge. The authors report a case of a 34 year old male complaining of painful perianal nodules for the three last years. Cutaneous histopathological examination was inespecific and colonoscopy normal. Pelvic CT scan and fistulography showed an intercommunicated fistular system invading both isquiorectal fossae, without intestinal communication. Repetition of colonoscopy showed normal mucosa, but in two of the biopsy samples noncaseous granulomas were found at the submucosa. The authors explain their main difficulties to reach the diagnosis of Crohn's disease and discuss the investigation and the evolution of the patient.