From the Guidelines
Distinguishing between Crohn's disease and tubercular abdomen is crucial, and a strong recommendation is to consider the differential diagnosis of tuberculosis in patients with suspected ileocaecal Crohn’s disease, particularly in those from endemic areas or with risk factors for infection, as stated in the British Society of Gastroenterology consensus guidelines 1.
Key Differences
To differentiate between the two conditions, several factors should be considered:
- Clinical presentation: Crohn's disease typically presents with abdominal pain, diarrhea, weight loss, and fatigue, while tubercular abdomen is characterized by chronic abdominal pain, fever, night sweats, and weight loss.
- Endoscopy and biopsy: Non-caseating granulomas are typical of Crohn's disease, whereas caseating granulomas are seen in tubercular abdomen.
- Imaging studies: Ileocecal involvement is common in both conditions, but it is more circumferential in tubercular abdomen.
- Laboratory tests: TB PCR performed on intestinal biopsies may be helpful for discrimination between the diseases, and a positive quantiferon gold test can suggest tubercular abdomen 1.
Diagnostic Approach
A combination of clinical evaluation, endoscopy with biopsy, imaging studies, and laboratory tests is necessary for accurate diagnosis.
- Features suggestive of intestinal TB include night sweats, concomitant pulmonary tuberculosis, positive tuberculin skin test, antibodies to TB, abdominal lymphadenopathy, ascites, transverse ulcers, and a patulous ileocecal valve 1.
- In contrast, features suggestive of Crohn's disease include anorectal lesions, longitudinal ulcers, aphthous ulcers, and cobblestoning on colonoscopy, as well as positive ASCA serology and proximal small bowel disease.
Treatment
Treatment for Crohn's disease and tubercular abdomen differs significantly:
- Crohn's disease is managed with anti-inflammatory medications, immunomodulators, and biologics.
- Tubercular abdomen is treated with standard anti-tubercular therapy, including isoniazid, rifampin, ethambutol, and pyrazinamide for 2 months, followed by isoniazid and rifampin for 4 additional months. Accurate differentiation between Crohn's disease and tubercular abdomen is essential to ensure appropriate treatment and prevent complications, and the British Society of Gastroenterology consensus guidelines provide a strong recommendation for considering the differential diagnosis of tuberculosis in patients with suspected ileocaecal Crohn’s disease 1.
From the Research
Differentiation between Crohn's Disease and Intestinal Tuberculosis
- The differentiation between Crohn's disease (CD) and intestinal tuberculosis (ITB) is often difficult due to similar clinical presentations, and requires a combination of clinical, endoscopic, serological, histological, and radiological parameters 2.
- Abdominal computed tomography (CT) scan is currently used as a first-line investigation for differentiating ITB from CD, while magnetic resonance imaging (MRI) is preferred in pediatric patients and for follow-up studies 2.
- Newer modalities like contrast-enhanced abdominal ultrasound, perfusion CT, advanced MRI, and positron emission tomography (PET) are evolving and require further exploration for their potential role in differentiating ITB from CD 2.
Role of Therapeutic Trial with Anti-Tubercular Therapy
- A therapeutic trial with anti-tubercular therapy can help differentiate ITB from CD, with ITB patients showing significant symptomatic response and endoscopic mucosal healing after 2-3 months of treatment 3.
- Patients with CD may show initial symptomatic response to anti-tubercular therapy, but mucosal healing is rare, and symptom persistence after 3 months of treatment may indicate CD 3.
Diagnostic Models and Parameters
- Various diagnostic models and scoring systems have been proposed to differentiate CD from ITB, using parameters such as clinical features, endoscopic and pathologic findings, high-resolution imaging, and serological testing 4.
- A combination of clinical, endoscopic, and CT enterographic parameters can help accurately diagnose CD or ITB, with a mathematical regression model showing high sensitivity, specificity, and accuracy 5.
- T-SPOT can be useful in excluding a diagnosis of ITB, but its sensitivity and specificity are lower than those of the combined parameter model 5.