Introduction: IBD usually presents with different phenotypes, which may include the presence of perianal disease. Although perianal disease is typical for patients with Crohn's disease, we should always pay the attention to the possibility of perianal disrase presence (hemorrhoids, anal fissure and/or fistula, perianal abscess) in patients with ulcerative colitis. In a certain number of patients with Crohn's disease, the perianal fistulas develop before the intestinal disease and the occurrence of perianal disease prior to development of ulcerative colitis is very rare.

Case presentation: We report a case of a 78-year-old female patient who was admitted to our hospital with the complaints of perianal pain, fever, rectal bleeding, abdominal cramps and progressively worsening bloody diarrhea. The results of diagnostic work-up was consistent with the diagnosis of ulcerative colitis and the presence of perianal disease in a form of anal fissure an rectocutaneous fistula. The treatment included the combination therapy of antibiotics, corticosteroids, 5-ASA compounds, and parenteral supplementation of packed erythrocytes, albumins and iron.

Conclusion: In presented older female patient with ulcerative colitis, the perianal disease was healed with combination therapy of antibiotics, corticosteroids and 5-ASA compounds, reflecting the difference in pathogenesis, clinical course and therapeutic response, compared to the nature of perianal disease in patients with Crohn's disease. The alternation of chronic constipation and diarrhea could be of pathogenetic influence in development of perianal disease, in this particular patient with ulcerative colitis.