Peritoneal Tuberculosis With a Clinical Presentation Mimicking Peritoneal Carcinomatosis

A.R., female, 50 years old, previously healthy, with complaints of increased abdominal volume, fatigue, and dyspnea on moderate exertion starting about one month earlier with progressive worsening. Evening fever up to 38°C was reported but infrequent. She denied other symptoms. Physical examination at admission: good general condition, distended and painless abdomen, with evident clinical signs of ascites. Abdominal and chest computed tomography confirmed large-volume ascites and bilateral pleural effusion, respectively. Laboratory tests: tumor marker CA 125 of 425 U/ml (normal ≤35). Transvaginal ultrasound showed endometrial thickening with heterogeneity and no ovarian abnormalities. She was evaluated by gynecology, which ruled out the hypothesis of primary gynecological pathology and suggested continuing the investigation. Ascitic fluid analysis showed SAAG <1.1, with lymphomononuclear predominance, ADA 67, CA 125 of 1,683, and negative oncotic cytology. The material was sent for investigation and culture for fungi, mycobacteria, including rapid molecular test for tuberculosis (Xpert MTB/RIF), and bacteria in general, in addition to complementary oncological analysis. The case was discussed with general surgery for diagnostic videolaparoscopy. Direct visualization of the peritoneum described multiple nodules covering the entire peritoneum, suggestive of carcinomatosis. Clinical and laboratory investigation for primary neoplasia was continued. Results of the remaining ascitic fluid tests: Xpert MTB/RIF positive. Histopathology described granulomatous peritonitis with focal necrosis and identification of some acid-fast bacilli (AFB) among the granulomas, with no evidence of neoplastic cells. Given the diagnosis of peritoneal tuberculosis, treatment was initiated with rifampicin (R), isoniazid (I), pyrazinamide (PZA), and ethambutol (E). The patient developed significant gastric intolerance and hepatotoxicity due to PZA, requiring adjustment of the regimen to RIE plus levofloxacin, with a planned therapeutic course of nine months. She evolved with excellent clinical response, regression of ascites and pleural effusion, and is currently in the maintenance phase with RI. Cases of peritoneal tuberculosis may occasionally present with elevated CA 125.