Peritoneal tuberculosis mimicking peritoneal carcinomatosis in a patient with T-cell lymphoma: Diagnostic pitfalls and radiologic correlation

Peritoneal tuberculosis (TB) can closely mimic peritoneal carcinomatosis on cross-sectional imaging, creating a major diagnostic dilemma in oncologic patients. We describe a 49-year-old man with refractory peripheral T-cell lymphoma who presented with progressive abdominal distension; contrast-enhanced CT showed bilateral pleural effusions, large-volume ascites, smooth peritoneal thickening with focal nodularity, omental infiltration, and necrotic mesenteric lymphadenopathy. Ascitic fluid testing revealed a lymphocyte-predominant exudate with elevated adenosine deaminase (ADA) and PCR positivity for <i>Mycobacterium tuberculosis</i>, confirming tuberculous peritonitis. The patient unfortunately deteriorated before specific therapy could be started. This case underscores the importance of integrating imaging, clinical history, and rapid microbiologic testing to avoid misclassification as peritoneal carcinomatosis and to guide timely management in immunocompromised patients.