eP750 - Perianal Fistula as a Tuberculosis Debut: When to Look for Zebras

Purpose/Background: In the United States (US), a non-healing perianal ulcer, abscess and/or fistula prompts investigation for Crohn’s disease (CD). Perianal tuberculosis (TB) is a rare cause of similar clinical scenarios. The incidence of TB in the US is low, with 2.5/100,000. Among the already uncommon extrapulmonary manifestations, perianal TB accounts for 0.7% of the cases [1]. Clinical diagnosis is challenging, and a subsequent colonoscopy often reveals normal macroscopic mucosa and skip lesions in the ileocecal valve, contributing to the overlapping characteristics between both entities. We describe a rare case of perianal fistulizing disease as the first clinical evidence of disseminated TB in the absence of previous pulmonary manifestation or known immunosuppressive state [2].Methods/Interventions: A 49 year old male with a history of hypertension and coronary artery disease presented to our clinic with a chronic fistula-in-ano status post multiple procedures by a local surgeon (including fistulotomy, seton placement, and advancement flap). On presentation to our institution, the patient complained of persistent pain and yellow discharge. Initial anorectal examination under anesthesia revealed a non healing wound at the attempted flap on the left lateral anterior perianal wound as well as a low left transsphincteric fistula with an external opening at the wound. Flexible sigmoidoscopy was normal to 30 cm from the anal verge. Two weeks later, a right sided lung nodule was found on chest X ray after a respiratory infection. The patient was treated for community acquired pneumonia and his symptoms resolved. He later endorsed weight loss and anemia. Repeat exam showed a continued nonhealing wound and two new fistula tracts in the right anal canal. A colonoscopy revealed no inflammation or ulceration in the colonic mucosa, but skip lesions in the ileocecal valve and terminal ileum, concerning for CD (Fig1,2). CT enterography confirmed similar inflammatory findings in terminal ileum. Biopsy of the lesions were positive for acid-fast bacteria. At this time, further workup for TB was completed which showed diffuse tree-in-bud opacities present in both lungs, as well as a positive PPD and QuantiFERON.Results/Outcomes: The patient was started on Rifampicin-Isoniazid-Pyrazinamide-Ethambutol (RIPE) therapy for 6 months. After 4 months of treatment his systemic symptoms improved and the perianal fistulotomy healed (Fig 2). His setons are still in place while awaiting completion of treatment and repeat endoscopic/imaging evaluation of resolution of ileal disease.Conclusion/

Discussion: To our knowledge, there have been less than 5 cases of perianal TB reported in the US. Perianal presentation prior to respiratory symptoms is even more rare. Regardless, cases of TB have risen over the past years, and this entity should be in the differential of non-healing fistulas. If not considered and ruled-out, a patient might begin immunosuppressive treatment under the misdiagnosis of CD, triggering severe consequences of disseminated TB [3]."Fig.1

Colonoscopy: Ileocecal valve lesions
Fig.2

Colonoscopy: Normal ileum
Fig.3

Physical exam 4 months after RIPE: Two healing fistulas in-ano"