Hidden in Plain Sight: Peritoneal Tuberculosis Mimicking Ovarian Neoplasm—A Case Report

Tuberculosis remains the deadliest infectious disease worldwide. Among extrapulmonary forms, peritoneal tuberculosis stands out as a rare and challenging diagnosis, often mistaken for intra-abdominal neoplasms or peritoneal carcinomatosis. The clinical, paraclinical, and imaging findings are similar and sometimes indistinguishable between the two entities, making the diagnosis a challenge for the treating physician. Here, we present the case of a young woman with chronic constitutional symptoms who presented to the emergency department with abdominal pain and ascites. An initial differential diagnosis of peritoneal carcinomatosis was considered based on findings in the peritoneal fluid and abdominal CT scan, leading to diagnostic laparoscopy. Histopathological examination of the samples revealed non-caseating granulomas involving the peritoneum, with no findings suggestive of malignancy. Subsequently, molecular testing for <i>Mycobacterium tuberculosis</i> was positive in the biopsies and peritoneal fluid, establishing the diagnosis of peritoneal tuberculosis. This case highlights the importance of awareness of peritoneal tuberculosis as a differential diagnosis of ascites and its significant potential to mimic other pathologies.