Abdominal Tuberculosis

Hannah Medeck; Harry Sell Jr.; Kurt Stahlfeld

Abdominal tuberculosis (ATB) comprises 5% of all tuberculous infections worldwide. Risk factors include cirrhosis, HIV, DM, underlying malignancy, malnutrition, treatment with anti-TNF agents, corticosteroids and continuous ambulatory PD. ^1,2 We present a case of ATB in a patient with no identifiable risk factors.

Case: A 48 yo female with a history of hypertension presented with abdominal pain, distention, weight loss, and new onset ascites. Computed tomography revealed multiple loculated fluid collections, peritoneal thickening, and mesenteric nodularity concerning for peritoneal carcinomatosis. Endoscopy, diagnostic paracentesis, and tumor markers were unremarkable. Diagnostic laparotomy revealed diffuse nodularity, 7 mm thick peritoneum, and sclerotic omentum densely adhered to small bowel. Pathology was negative for malignancy but peritoneal fluid was positive for lymphocytosis, elevated adenosine deaminase (ADA) level at 93 U/L, and a positive AFB stain for mycobacterial cells, highly suspicious for ATB.

Discussion: ATB involving the peritoneum, intestinal tract, hepatobiliary tree, pancreas, perianal area, or lymph nodes occurs via reactivation of latent TB or ingestion of TB mycobacteria. Symptoms include fever, weight loss, abdominal pain, distention, ascites, hepatomegaly, diarrhea, bowel obstruction, or an abdominal mass.³ Abdominal CT may reveal ascites, lymphadenopathy, and thickening of the mesentery, omentum, and peritoneum.⁴ Operative findings are nonspecific dense adhesions. Ascitic fluid in ATB is exudative with a leukocyte count between 150-4000 cells/mm3, ADA greater than 40 IU/L, and may stain positive or culture AFB. Sensitivity and specificity approaches 100% for an elevated ADA, compared to that of a positive stain (2%) or mycobacterial culture (20%).The principal biological activity of ADA is related to the proliferation and differentiation of T cell lymphocytes involved in a response of cell mediated immunity to mycobacterial antigens.¹⁰ Treatment parallels that of pulmonary TB with six months of multidrug therapy. Our patient had no identifiable risk factors.

ATB is rare in an immunocompetent patient. Given the prolonged time to return a positive AFB culture, mortality is high. The diagnosis requires a high index of suspicion in a patient with new-onset ascites, peritoneal thickening of unclear etiology, and negative malignancy workup. Multidisciplinary interactions with infectious disease and pathology may be beneficial.