Tuberculous peritonitis with infracarinal mass and elevated CA-125 in a 13-year-old girl.

A 13-year-old girl with weight loss and ascites was admitted with suspicion of a malignant disease. Abdominal magnetic resonance imaging indicated extensive peritonitis and showed no evidence of a solid tumor. As a new imaging observation, thoracic computed tomography showed a lymphoma-like infracarinal mass and further enlarged lymph nodes in the pathway of draining lymph ducts. A tuberculin skin test and an interferon-gamma blood test were positive, and the tumor marker CA-125 was elevated. Histology of a peritoneal biopsy showed infectious granulomas with central necrosis, and Mycobacterium tuberculosis could be cultured, leading to the diagnosis of a tuberculous peritonitis. The girl received multi-drug anti-tuberculous treatment and subsequently recovered. At follow-up the peritonitis and the infracarinal mass had vanished. In conclusion, tuberculous peritonitis is a rare but relevant differential diagnosis in peritonitis of unknown origin. Its diagnosis is facilitated by imaging, by tuberculosis skin and blood tests, and by clinical interpretation.