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Abdominal Tuberculosis Presenting as a Malignant Masquerader

Axial view of the computed tomography scan of abdomen upon initial presentation, revealing a peripancreatic versus pancreatic mass (single arrow) and liver lesions (double arrow).

Axial view of the computed tomography scan of abdomen upon initial presentation, revealing a peripancreatic versus pancreatic mass (single arrow) and liver lesions (double arrow).

 

A previously healthy, immunocompetent, US-born, 48-year-old black woman presented with 6 months of subjective fevers, night sweats, and intermittent abdominal pain. Initial computed tomography scan (Figure 1) revealed a pancreatic versus peripancreatic mass and multiple liver lesions concerning for metastatic pancreatic cancer; percutaneous fine-needle aspiration (FNA) of the liver lesions revealed inflammatory changes and no cancer. As her pain worsened, a follow-up computed tomography scan 3 months later (Figure 2) revealed an enlarging peripancreatic mass (single arrow) but resolution of liver lesions (double arrow). Endoscopic ultrasound FNA of a 5 × 5-cm periportal lymph node aggregate (Figure 3) revealed histologic features consistent with necrotizing (caseating) granulomatous inflammation. An acid-fast bacillus stain was negative, but a purified protein derivative skin test and serum Quantiferon-TB test results were positive; empiric coverage for mycobacterial infection was started. Three weeks after FNA, fungal culture from the endoscopic ultrasound aspirate confirmed the presence of Mycobacterium tuberculosis (TB).

The prevalence of TB is more common among immunocompromised patients. Since the 1992 peak of TB resurgence and the acquired immune deficiency epidemic, the rate of reported cases of TB has declined, although the TB case rate among foreign-born persons is substantially higher than in US-born persons. One of the most common extrapulmonary involvements of TB is the abdomen, but it is relatively infrequent in the United States and is classified by its area of involvement. A review of 596 abdominal TB patients revealed that the majority (92%) involved the gastrointestinal tract and peritoneum, and rarely in the mesenteric lymph nodes, as presented in our case.

Overall, abdominal TB poses a few challenges for physicians. First, it lacks specific symptoms or signs; in fact, a case series revealed a lack of abdominal findings among approximately one-third of immunocompromised patients diagnosed with abdominal TB. Second, confirming the diagnosis can be a challenge, because there is high variability in the yield of specimen histology, smear, and culture. We required other diagnostic tests, such as purified protein derivative skin test and serum Quantiferon-TB, to increase our level of suspicion and start treatment after the FNA was negative, but cultures eventually grew. Last, if the area of interest is not within easy reach, it also adds difficulty in achieving diagnosis.

Although abdominal TB is an exceedingly rare disease, our case underscores the importance of maintaining a high index of awareness, leading to decreased morbidity and treatment delay even in a nonimmigrant and immunocompetent patient.

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-Alejandro L. Suarez, MD, Gregory A. Coté, MD, MS

This article originally appeared in the October 2016 issue of The American Journal of Medicine.

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