S2456 TB or Not TB? Miliary Tuberculosis in a QuantiFERON-Indeterminate Patient on Infliximab Therapy

Abstract

Introduction: Miliary tuberculosis results from massive hematogenous dissemination of tuberculosis (TB) typically to the lung, bone, and less commonly to the gastrointestinal tract. It accounts for 2% of TB cases which may present as a life-threatening septic shock in the setting immunosuppression. Case Description/Methods: A 53-year-old Cuban male physician with moderate to severe ileocolic Crohn's disease and a history of travel to Cuba was recently initiated on Infliximab due to the failure of conventional therapy. Pretreatment Interferon-γ Release Assay (IGRA) QuantiFERON-TB Gold In-Tube, and tuberculin skin test were negative. Fourteen weeks later, he reported fever, emesis, and unintentional weight loss. Colonoscopy revealed severely inflamed mucosa of the right hemi-colon promoting escalation of infliximab dose with steroids for a presumed CD flare. Biopsy subsequently revealed numerous acid-fast bacilli. Therapy was immediately aborted, and he was then advised to initiate TB treatment. He returned eight days later with shock progressing to multiorgan failure. During emergent exploratory laparotomy, the small bowel and omentum were studded with white granulomatous nodules. He expired n the first postoperative day. Sputum, omentum, and abdominal wall cultures were all positive for Mycobacterium tuberculosis, and repeat IGRA was indeterminate. Discussion: Crohn’s disease (CD) is a chronic granulomatous inflammatory and destructive disease which follows a relapsing and remitting course. Infliximab therapy is initiated in moderate to severe stages however it carries with it an increased risk of reactivation of latent TB. IGRA testing before and during treatment is important during treatment with infliximab. It is difficult to surmise whether the subsequent hospital visits post infliximab initiation were due to worsening CD, or a manifestation of intestinal TB given the striking similarities. This patient’s insidious weight loss and rapid decline concomitant with the escalation of Infliximab and corticosteroid use points towards intestinal TB as the etiology of the symptoms. Despite the high sensitivity of IGRA testing, this patient’s travel history in an endemic area decreases the negative predictive value of the test. Diagnosis of miliary TB is challenging given its nonspecific presentation and limited diagnostic modalities. Therefore, patients continually exposed to endemic areas should prompt more frequent diagnostic re-evaluation prior to Infliximab escalation.