Clinical updates on perianal fistulas in Crohn's disease.

INTRODUCTION: Perianal fistulizing disease is an aggressive and debilitating phenotype of Crohn's disease (CD), representing a significant therapeutic challenge. New work has led to advancement in epidemiology and long-term outcomes of perianal disease. The range of therapeutic options continues to expand, including new biologic agents, biosimilars, and stem cell therapy. Areas covered: We discuss updates to all aspects of management of perianal disease, with a focus on the last 3 years of published data. Areas considered include new data on epidemiology and prognostication, medical and surgical therapy, and stem cell therapy. Expert commentary: The presence of perianal disease at CD diagnosis portends a significantly worse disease course. Patients with perianal disease require close monitoring to identify those who are at risk for worsening disease, suboptimal biologic drug levels, and signs of developing neoplasm. With the impending availability of local mesenchymal stem cell therapy, this becomes increasingly important as this therapy, although extremely promising, is thus far only effective in patients without proctitis.