Clinical Course of Isolated Recurrent, Persistent Complex Perianal Fistulas Without Luminal Crohn's Disease: A Multicenter Case Series of 24 Patients.

Background: Isolated complex perianal fistulas, without luminal evidence of inflammatory bowel disease in the gastrointestinal tract, pose diagnostic and treatment dilemmas for gastroenterologists and colorectal surgeons. For patients who develop recurrent complex fistulas, a presumptive diagnosis of Crohn's disease may be made. It is unclear whether these cases of isolated perianal disease in the absence of luminal inflammation truly represent isolated severe cryptoglandular fistulas or rather an early presentation of Crohn's disease. We aimed to investigate the clinical course and outcomes of patients with isolated complex perianal fistulas.

Methods: In this retrospective multicenter case series across 6 institutions in the United States, we report the clinical course of patients with isolated recurrent complex perianal fistulas, including their diagnostic evaluation, medical and surgical therapies, and clinical outcomes.

Results: All patients (n = 24) required incision and drainage of perirectal abscesses. The majority received setons (n = 19, 79%), more intensive surgical interventions (n = 15, 62.5%, including fistulotomy/sphincterotomy, advancement flap, and ligation of the intersphincteric fistula tract), antibiotics (n = 17, 71%), and biologic therapy (n = 16, 67%). Nine patients (37.5%) underwent a combined medical-surgical approach with biologics and intensive surgical intervention. Despite surgical and/or medical management, active symptomatic complex perianal fistulas persisted in 58% (n = 14) of patients at follow-up (median 5.5 years, interquartile range 2.5-10 years); symptom remission was achieved in 21% (n = 5), and fistula closure in 21% (n = 5).

Conclusions: These cases highlight a multidisciplinary and multimodal approach when treating isolated complex perianal fistulas and their propensity to persist despite the incorporation of advanced therapies.