Tuberculosis and Crohn's Disease Revisited.

Crohn's Disease (CD) and Intestinal Tuberculosis (ITB) share confusingly similar clinical, endoscopic, radiological and pathological manifestations. There is no simple test for differentiating ITB from CD. Although there are a number of sensitive and specific parameters for distinguishing between CD and ITB, the differential diagnosis still remains challenging and both clinical suspicion and appropriate clinical and laboratory studies are required to establish the diagnosis. Correct diagnosis is crucial because the therapy strategies of the two diseases are dramatically different. Treatment of ITB with immunosuppressive agents would lead to worsening of the patients' condition. Likewise, unnecessary antituberculosis therapy would delay the treatment of CD. Another important consideration is the risk of reactivation TB in patients with inflammatory bowel diseases which has been significantly increased following the widespread use of anti-Tumor Necrosis Factor Alpha (TNF-α) therapy. The majority of reactivation cases are extrapulmonary or disseminated TB. And it is widely recommended that patients with IBD who are to receive TNF inhibitor therapy should be screened for evidence of latent TB. This paper mainly reviews current literature on differential diagnosis between CD and ITB, and summarizes strategies to reduce the TB risk among candidates for TNF antagonist therapy in this specific patient population.