CT Abdomen & Pelvis - Clinical Analysis

Key CT Findings

Probable Diagnosis: Intestinal Tuberculosis (Colonic TB)

Why Intestinal TB?

1. Distribution pattern - Cecum + ascending colon + transverse colon involvement is classic for colonic TB. The Sleisenger & Fordtran textbook states that the ileum and cecum are the most common sites (75% of cases), and colonic TB can show "extensive involvement of the cecum, ascending, and transverse colon."
2. Circumferential wall thickening - Consistent with the ulcerohypertrophic form of intestinal TB (30% of cases), which combines mucosal ulceration with healing and fibrosis.
3. Calcified hepatic granulomas - Multiple subcentimeter calcified granulomas in the liver are a hallmark of healed hepatic TB (or histoplasmosis in endemic areas, but TB is far more likely in India). These indicate prior or concurrent mycobacterial infection and strongly support a TB etiology.
4. Young patient in an endemic region - India has the world's highest TB burden; a 20-year-old presenting with colonic inflammation + hepatic granulomas is highly suspicious.
5. No lymphadenopathy on CT - Note that enlarged/necrotic mesenteric nodes are a major CT feature of intestinal TB, but their absence does not exclude the diagnosis (early disease or treated TB).

Differential Diagnoses

Recommended Diagnostic Workup

Immediate (to confirm diagnosis)

• Colonoscopy with biopsy - the most important investigation. Biopsy for:
  • Histopathology (look for caseating granulomas)
  • AFB (Ziehl-Neelsen) stain
  • Mycobacterial culture and drug sensitivity testing
  • TB-PCR on biopsy tissue (sensitivity ~65%)
• Mantoux test / IGRA (QuantiFERON-TB Gold) - to detect M. tuberculosis infection
• Chest X-ray / HRCT chest - to look for concurrent pulmonary TB
• Sputum AFB smear + culture (if pulmonary involvement suspected)
• Stool AFB culture
• CBC, ESR, CRP, LFT, serum albumin
• HIV serology (immunocompromise workup)
• Serum ADA (Adenosine Deaminase) - elevated in TB
• If granulomas found on biopsy - ACE levels to also rule out sarcoidosis

Treatment

If Intestinal TB confirmed:

• Isoniazid (H) + Rifampicin (R) + Pyrazinamide (Z) + Ethambutol (E)
• Written as 2HRZE

• Isoniazid (H) + Rifampicin (R)
• Written as 4HR

Note: If response to therapy occurs (within 2 weeks typically), this can also be used as a confirmatory therapeutic trial. However, culture confirmation is strongly preferred before initiating treatment when possible.

Additional management:

• Nutritional support - correct malnutrition/hypoalbuminemia
• Pyridoxine (Vitamin B6) - given alongside isoniazid to prevent peripheral neuropathy (10 mg/day)
• Monitor LFTs monthly for drug-induced hepatotoxicity (especially with INH + RIF + PZA)
• Public health notification - TB is a notifiable disease
• Contact tracing of household members

If Crohn's Disease confirmed (on biopsy):

• 5-ASA (mesalazine) for mild disease
• Corticosteroids for moderate-active disease
• Immunomodulators (azathioprine, 6-MP) for maintenance
• Biologics (anti-TNF) for severe/refractory disease
• Important caveat: Do NOT start steroids or immunosuppressants before excluding TB - this can cause fatal dissemination of occult TB.

Summary

References: Sleisenger and Fordtran's Gastrointestinal and Liver Disease (9780323609623) - Tuberculosis of the Intestinal Tract; Jha et al. 2023 - Evidence-based approach to diagnosis and management of abdominal tuberculosis; Choudhury et al. 2023 - Differentiating GI tuberculosis and Crohn's disease

Disclaimer: This analysis is for educational and clinical decision support purposes. The treating physician should integrate this with the full clinical history, examination findings, and local epidemiology before making management decisions.