Case Presentation: A 33-year-old Filipino male with prior long history of latent tuberculosis, active smoking who presented with one month of progressive abdominal pain, decreased appetite, weight loss, and new periumbilical bruising. Examination revealed a thin, afebrile man with distended abdomen, shifting dullness, and periumbilical ecchymosis. Laboratory studies showed microcytic anemia and thrombocytosis otherwise unremarkable. CT and MRI of the abdomen/pelvis demonstrated ascites and findings concerning peritoneal carcinomatosis. Paracentesis revealed low-SAAG, lymphocytic-predominant fluid with elevated protein and adenosine deaminase. Fluid cultures and AFB smears were negative. Definitive diagnosis was made on peritoneal biopsy, which showed necrotizing granulomas and acid-fast bacilli and positive MTB PCR, confirming peritoneal tuberculosis. Surprisingly, chest x-ray was negative for pulmonary infiltrates. The patient was started on standard RIPE therapy but developed hepatotoxicity requiring temporary discontinuation and outpatient follow up.
Discussion: Peritoneal tuberculosis is an uncommon form of extrapulmonary tuberculosis and often mimics peritoneal carcinomatosis, leading to diagnostic delay. Chronic ascites in the absence of liver disease is the most frequent manifestation [1]. Risk factors include HIV infection, diabetes mellitus, treatment with anti–tumor necrosis factor, and hepatic cirrhosis [2]. Early recognition requires careful integration of demographic, clinical, and diagnostic data. Peritoneal tuberculosis frequently resembles malignancy on imaging and may have nondiagnostic ascitic fluid studies. Diagnosis is often delayed or missed due to non-specific clinical presentation, long incubation period for AFB cultures which takes 4–8 weeks, and high false-negative rates of AFB smears leading to a delay in starting treatment. Thus, when clinically suspected, a tissue biopsy is necessary for confirmation. Patients from TB-endemic regions remain at risk for reactivation, even years after treatment, and we should have a high degree of suspicion depending on the clinical picture. Although immunosuppression is the leading cause of reactivation, one should maintain suspicion even with immunocompetent patients as in our case. A lymphocyte-predominant, low-SAAG ascites should heighten suspicion. The elevated adenosine deaminase returned later but supports further workup [3–5].
Conclusions: This case highlights the importance of maintaining clinical suspicion for peritoneal tuberculosis in patients with epidemiologic risk factors and ascites of unclear etiology, particularly when imaging suggests carcinomatosis but routine studies are nondiagnostic. Early biopsy and timely management are important for preventing morbidity.