Resumen esto en lo mas importante Tuberculosis is a primary differential diagnosis of IBD
in patients in endemic areas, in patients migrating
or travelling from endemic areas, and in immunocompromised individuals.7
 The pathophysiological
mechanisms of intestinal tuberculosis transmission
include the ingestion of infected sputum or contaminated
beverages, but the disease can also be haematogenous or
spread directly from adjacent organs in an individual
with tuberculosis.8
 The clinical presentation of intestinal
tuberculosis can be very similar to that of Crohn’s
disease, including lower abdominal pain, weight loss,
and diarrhoea.8
 Laboratory tests, including serological
markers for anti-neutrophil cytoplasmic antibodies and
anti-S cerevisiae antibodies, have no substantial value in
discriminating between intestinal tuberculosis and IBD.9
The tuberculin skin test has limited value, especially
in BCG-vaccinated populations because of a high
false-positive rate.10 The interferon-γ release assay does
not cross-react with BCG or with non-tuberculous
mycobacteria and is clinically useful for differentiation of
intestinal tuberculosis from IBD. However, the assay’s
sensitivity to detect intestinal tuberculosis remains as
low as 67%.11 Remarkably, a chest x-ray is indicative of
active pulmonary involvement in only 20–25% of patients
with intestinal tuberculosis.8
 In abdominal imaging, the
Lancet Gastroenterol Hepatol
2018; 3: 644–53
Department of
Gastroenterology and
Hepatology, Academic Medical
Center, Amsterdam,
Netherlands (K B Gecse MD)
and Department of
Gastroenterology and
Hepatology, University
Hospitals Leuven, Leuven,
Belgium (Prof S Vermeire MD)
Correspondence to:
Prof Severine Vermeire,
Department of Gastroenterology
and Hepatology, University
Hospitals Leuven, 3000 Leuven,
Belgium
<PRESIDIO_ANONYMIZED_EMAIL_ADDRESS>
www.thelancet.com/gastrohep Vol 3 September 2018 645
Review
presence of asymmetric wall thickening and enlarged
necrotic mesenterial lymph nodes is highly suggestive
of intestinal tuberculosis.7
 By contrast, symmetric
bowel wall thickening, segmental involvement, fistula
formation, increased mesenteric vascular stranding
(so-called comb sign), and fibrofatty proliferation of the
mesentery are indicative of Crohn’s disease.12 Endoscopic
features that might raise the suspicion of intestinal
tuberculosis include transversal ulcers, pronounced
scarring, and a patulous aspect of the ileocaecal valve
(figure 1).13 By contrast, endoscopic predictors of Crohn’s
disease include left colon involvement, colonic skip
lesions, and superficial, aphthous, or linear ulcerations.14
Combining the findings of ileocolonoscopy and CT
enterography can raise the accuracy of diagnosis to
differentiate between Crohn’s disease and intestinal
tuberculosis from 67% to 95%.12 In haematoxylin and
eosin staining, intestinal tuberculosis can be characterised by confluent and caseating granulomas (in
contrast to non-caseating granulomas in Crohn’s
disease), and Ziehl-Neelsen staining can reveal acid-fast
bacilli. However, the accuracy of conventional histopathology remains low. Biopsy culture for Mycobacterium
tuberculosis is time consuming (3–8 weeks), with low
accuracy (25–35%).15 Tuberculosis PCR from biopsy or
resection specimens has a high accuracy for diagnosing
intestinal tuberculosis. Additionally, the GeneXpert
MTB/RIF assay (Cepheid, Sunnyvale, CA, USA) uses
real-time PCR to amplify a gene sequence specific to
M tuberculosis and is capable of assessing rifampicin
resistance with 97% sensitivity in pulmonary tuberculosis.16 For extrapulmonary tuberculosis, the assay
correctly identified approximately 80% of culture-positive
specimens.17 A Bayesian model based on meta-analyses
has been suggested to be able to estimate the probability
of intestinal tuberculosis and Crohn’s disease, calibrated
to local prevalence.18 This validated tool showed
92% accuracy for the diagnosis of intestinal tuberculosis
and is publicly available as a web application. Intestinal
tuberculosis, similarly to pulmonary tuberculosis, is
treated with a combination therapy, in which the
first-line treatment is comprised of rifampicin, isoniazid,
ethambutol, and pyrazinamide. Drug resistance, contraindication, or intolerance can warrant the substitution for
second-line agents, such as fluoroquinolone antibiotics or
ethionamide. The anti-tuberculosis regimen consists of
two phases: an intensive phase (2 months) and a
maintenance phase (4–7 months), with most patients
receiving a 6-month regimen.19 Screening for latent
tuberculosis should be done in all patients before starting
immunosupressive anti-tumour necrosis factor (TNF)
treatment for IBD.20