Peritoneal Tuberculosis in a Patient on Tumor Necrosis Factor inhibitors: A Case Report and Review of the Literature.

Peritoneal tuberculosis (PTB) is a diagnostic challenge due to its nonspecific presentation, low sensitivity of ascitic fluid microbiologic tests, and possible resemblance to peritoneal carcinomatosis. We describe a case of 51-year-old woman with long-term tumor necrosis factor alpha (TNF-α) inhibitor exposure presented with fever and abdominal distension after returning from the Philippines. Initial tests, including microbiological studies, were inconclusive, despite imaging findings suggestive of carcinomatosis with elevated CA-125. Diagnostic laparoscopy revealed miliary white nodules; however, omental biopsy showed non-necrotizing granulomas without AFB. High clinical suspicion prompted excision of an enlarged axillary lymph node, which demonstrated necrotizing granulomas with rare AFB-positivity and ultimately grew Mycobacterium tuberculosis. The patient experienced rapid symptomatic relief and near-complete radiological resolution within four months of tuberculosis (TB) treatment. PTB should remain on the differential for unexplained ascites or peritoneal nodularity - particularly in immunosuppressed travelers from endemic regions - even when early microbiologic tests are negative. Timely invasive sampling and, when warranted, empirical anti-TB therapy is critical. Clinicians must recognize that patients on TNF-α inhibitors remain at heightened risk for extrapulmonary TB despite negative baseline screening.