Brown University/Rhode Island Hospital Providence, RI
Introduction: Isolated complex perianal fistulas are abnormal connections between the epithelial surfaces of the anal canal and the perianal skin, meeting criteria for complex perianal fistula but without evidence of inflammatory bowel disease (IBD). While over half of patients with Crohn’s disease (CD) have perianal fistulas, isolated perianal CD is rare. Here we discuss five cases of patients presenting with isolated recurrent complex perianal fistula, and we describe their diagnostic evaluation, attempted therapies, and outcomes.
Case Description/Methods: Five adults (3 women, 2 men; mean age 38 years old) with no prior GI symptoms/diseases initially presented with perianal pain (3/5), perirectal mass (2/5), diarrhea (1/5), and abdominal pain (1/5) (Table 1). All patents underwent exam under anesthesia (EUA) with incision and drainage (I&D) of perirectal abscesses, and setons were placed in perianal/rectal fistulas in 4/5 cases. Each patient had colonoscopy without evidence of inflammation on endoscopy or histology. Radiographic imaging (MRIs, MREs, and CT) revealed fistulas and abscesses but no evidence of luminal inflammation. All patients were treated with antibiotics and 4/5 received biologic therapy (Adalimumab, Infliximab, or Ustekinumab). Despite surgical and medical management, complex perianal fistulas were persistent in all patients at follow-up after an average of 45 months.
Discussion: For patients who develop recurrent complex fistulas, a presumptive diagnosis of CD is often made. However, patients who present with complex perianal fistulas in the absence of the luminal inflammation characteristically found in CD are said to have isolated perianal disease (IPD). It is unclear whether IPD represents truly isolated severe cryptoglandular fistulas or early presentation of undiagnosed CD, which renders the best treatment approach a clinical dilemma. IPD is classically treated with antibiotics and local surgical intervention, whereas perianal CD treatment is more complex, incorporating the use of immunosuppressive therapy. The cases described in our cohort reveal the importance of a multimodal approach when treating IPD in the absence of luminal findings of CD. While classic medications for CD are unlikely to succeed when used alone for IPD, their incorporation into the treatment regimen may be critical in achieving eventual resolution of perianal disease. Given the similarity in management, it is important to consider CD in the differential for IPD patients even in the absence of luminal findings.
