Case Presentation: This is a 32 year old female with no significant past medical history who presented with diffuse, constant, dull abdominal pain. She denied any associated diarrhea, fever, chills, night sweats, or weight loss. Her social history was significant for immigrating from Trinidad when she was eight years old. She had previously been admitted for a similar episode 5 months prior and was found to have necrotizing right lower quadrant portacaval and mesenteric adenopathy and mural thickening of terminal ileum and cecum on CT abdomen/pelvis. The initial working diagnosis was Crohn’s disease so a quantiferon gold was obtained in preparation for possible treatment with immunosuppressive therapy. Her test was subsequently found to be positive which raised the suspicion for tuberculosis (TB). Colonoscopy revealed mucosal ulcerations consistent with Crohn’s disease versus intestinal TB (ITB) and biopsies were obtained. While waiting for biopsy and culture results, she was discharged with close follow up. Her MTB PCR was negative but her TB culture was cancelled for unclear reasons. On physical exam, patient’s vital signs were within normal limits. Abdominal exam revealed diffuse tenderness to palpation without guarding or rebound. She had normal bowel sounds. Labs showed elevated ESR of 74 and CRP of 86.1. She underwent a repeat CT abdomen/pelvis which was unchanged from her prior imaging. Differential diagnosis remained to be Crohn’s disease versus ITB. Infectious Disease (ID) was consulted who recommended holding immunosuppression for Crohn’s disease until TB was absolutely ruled out. She underwent a repeat colonoscopy and biopsy with AFB smear and culture. She was discharged with outpatient follow up. During ID follow up, she was empirically started on RIPE 4 drug TB therapy due to high clinical suspicion for ITB. Patient reported symptomatic improvement after three weeks of therapy. One week later, AFB cultures from her tissue biopsy came back positive and a final diagnosis of ITB was established.
Discussion: The diagnosis of ITB has been proven to be challenging as its symptoms and presentations tend to be non-specific and mimic other diseases, such as inflammatory bowel disease (IBD) or malignancies. There is no single gold standard diagnostic test but rather a consolidation of symptoms, imaging, and histopathology. Interferon gamma release assays (IGRAs) or PPD have been used to screen for TB. Both tests are fairly sensitive (80-90%, 80%, respectively) but are not diagnostic for active TB. As a result, further testing is warranted to differentiate between ITB and IBD. Unfortunately, current available tests, including MTB PCR, AFB staining, and TB culture, all have low sensitivities (25%, 38%, 50%, respectively). Furthermore, sampling error may result in even lower sensitivities. Therefore, repeat biopsies with tissue AFB staining, MTB PCR, and TB culture may increase sensitivities of the tests. If clinical suspicion is high in the setting of negative diagnostic tests, empiric RIPE therapy for ITB is recommended as misdiagnosis can lead to devastating consequences.
Conclusions: It is challenging to differentiate ITB and IBD as imaging can be non-specific and diagnostic studies such as MTB PCR, AFB staining, and culture have low sensitivities. Repeat TB tests may increase the sensitivity of ITB diagnosis. Empiric anti TB therapy is recommended if clinical suspicion is high for ITB despite inconclusive test results.