Individual case: Intestinal tuberculosis

A patient with intractable abdominal pain and non-bloody, watery diarrhea who recently immigrated from Cuba.


The patient

A 33-year-old man presented with one month of intractable abdominal pain that began with nausea and vomiting and progressed to include diarrhea. He had been admitted a week prior for similar symptoms and sent home with oral antibiotics for presumed bacterial gastroenteritis after CT scan showed nonspecific terminal ileitis. On re-presentation, he reported sharp abdominal pain associated with several episodes of non-bloody, watery diarrhea. His social history was remarkable for a 30 pack-year smoking history and immigration from Cuba three months earlier.

On presentation, he was afebrile with a blood pressure of 100/65 mm Hg and a heart rate of 111 beats/min. Initial labs were significant for a hemoglobin level of 10.8 g/dL (reference range, 12 to 16 g/dL), a hematocrit of 32.9% (reference range, 35% to 47%), an aspartate aminotransferase level of 43 units/L (reference range, 10 to 40 units/L), and an albumin level of 2.2 g/dL (reference range, 3.2 to 5.0 g/dL). Physical exam was significant for a soft, mildly distended abdomen with diffuse tenderness on palpation (although greatest in the epigastric area), no rebound tenderness, and negative Murphy's sign.

Figure 1 CT of the abdomen demonstrating a necrotic mass with circumferential enhancement arrow
Figure 1. CT of the abdomen, demonstrating a necrotic mass with circumferential enhancement (arrow).
Figure 2 Colonoscopy image with localized inflammation erythema and granularity found in the terminal ileum arrow
Figure 2. Colonoscopy image, with localized inflammation, erythema, and granularity found in the terminal ileum (arrow).

A repeat CT scan of the abdomen (Figure 1) demonstrated multiple new necrotic masses with central fluid density and circumferential enhancement noted throughout the mesentery and retroperitoneum. A colonoscopy showed ileitis (Figure 2) with acute inflammation on biopsy, and a CT-guided biopsy of a lymph node found no immediate growth of an organism. Due to the suspicion of possible malignancy, the patient underwent hemicolectomy. The preliminary pathology report of the ileum demonstrated nonspecific inflammation suggestive of Crohn's disease; however, final evaluation several weeks later revealed samples were positive for acid-fast bacilli (AFB). A chest CT found “tree-in-bud” opacities in bilateral upper lobes. Bronchoalveolar lavage was initially negative on AFB smear testing, but cultures grew Mycobacterium tuberculosis complex five days later. An HIV test was positive. Appropriate anti-tubercular treatment was initiated. The patient's condition improved and he was discharged with appropriate anti-tuberculosis medication and referred to infectious disease outpatient follow-up.

The diagnosis

The patient was diagnosed with intestinal tuberculosis (ITB), a form of extrapulmonary tuberculosis. ITB is the sixth most prevalent form of extrapulmonary tuberculosis found worldwide, and its incidence is rising in those who are immunocompromised. ITB most commonly involves the ileocecal region, followed by the jejunum and colon. The terminal ileum is most commonly affected due to the abundance of lymphoid tissue present, increased absorption rate, and closer contact between the bacilli and mucosa. Given the predilection for the terminal ileum and endoscopic similarities, it is often misdiagnosed as Crohn's disease, especially when there is lack of suspicion for ITB. A short, single stricture in the terminal ileum involving the ileocecal junction with the presence of necrotic lymph nodes (≥1 cm) suggests tuberculosis as its primary source; long strictures and/or strictures affecting more than three ileal segments, with skip lesions and engorged vasa recta, are more suggestive of Crohn's disease.

Diagnosis of ITB can be a challenge given nonspecific clinical symptoms, laboratory and radiological studies, and endoscopic findings. Suggestive radiographic findings (which on CT include asymmetrical circumferential wall thickening of the cecum and terminal ileum with mesenteric lymphadenopathy) plus histopathological results are needed to make an accurate diagnosis. Polymerase chain reaction testing for tuberculosis may provide a rapid diagnosis, but its sensitivity is 40% to 75% for endoscopically-biopsied material. A positive tuberculosis culture remains the diagnostic gold standard. Standard anti-tuberculosis treatment is used for ITB. Treatment length does not change with co-existence of ITB with pulmonary tuberculosis; the standard remains six to nine months. Longer treatment (12 months) is only indicated for central nervous system infection. Overall prognosis varies based on host factors, although untreated disseminated tuberculosis has been associated with death within one year.

Pearls

  • ITB is the sixth-most prevalent form of extrapulmonary tuberculosis found worldwide, and its incidence is rising in immunocompromised patients.
  • ITB most commonly involves the ileocecal region and is often misdiagnosed as Crohn's disease; treatment agents and duration are the same as for pulmonary tuberculosis infection.

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