Where is the Bacillus: A Case of Tuberculous Peritonitis

Abstract

Purpose: A 61-year-old Cambodian female with a history of chronic Hepatitis B related cirrhosis presented with 1 month of progressive dyspnea and increasing abdominal girth. There was no history of encephalopathy, bleeding, jaundice, edema or ascites. She denied fevers, weight loss or abdominal pain. She had a positive purified protein derivative (PPD) skin test for which she received 9 months of isoniazid therapy 10 years before. On examination, her abdomen was distended with a palpable fluid thrill and normoactive bowel sounds. Laboratory studies showed a WBC count of 6600 with 83% neutrophils, AST 71 U/L (normal, 8-43 U/L), ALT 23 U/L (normal, 7-45 U/L) and Alkaline phosphatase 59 U/L (normal, 41-108 U/L). Abdominal computed tomography showed hepatic cirrhosis and ascites. Paracentesis with removal of 4 Liters of serous fluid resulted in a rapid improvement of dyspnea. Ascitic fluid showed a serum ascitic albumin gradient (SAAG) of 1.1, total protein 3.4 g/dL and 487 nucleated cells with 69% lymphocytes. Given the high protein, lymphocytic ascites and the history of positive PPD, tuberculous peritonitis was suspected. Acid fast bacillus (AFB) stain and Mycobacterium tuberculosis (MTB) PCR on ascitic fluid were negative. Chest x-ray showed bibasilar atelectasis. Three sputa for AFB stain and MTB PCR were negative. Laparoscopy showed white tubercles in the abdomen. Pathology showed non necrotizing granulomatous inflammation with negative AFB stain, MTB PCR and fungal stains. Despite a high initial suspicion for tuberculous peritonitis, no confirmatory evidence was found, prompting a search for alternative diagnoses. Ascitic fluid cytology did not show malignant cells. An ACE level was 23 micrograms/L (normal, <40 micrograms/L). Fungal and autoimmune serologies were negative as well. Despite the absence of a diagnosis, the patient was doing well clinically and was dismissed with out-patient follow up. After 6 weeks, AFB cultures from the peritoneal biopsies grew Mycobacterium tuberculosis, confirming a diagnosis of tuberculous peritonitis. Tuberculous peritonitis is an uncommon form of extrapulmonary tuberculosis. The diagnosis should be suspected based on a high protein ascitic fluid with a lymphocytic pleocytosis. The SAAG is typically <1.1 but can be >1.1 in patients with cirrhosis. However, making a definitive diagnosis can be both challenging and tardy since ascitic fluid has a low sensitivity for detecting the bacillus. A peritoneal biopsy with mycobacterial culture is necessary to make the diagnosis in most cases. The risk of tuberculous peritonitis is increased in cirrhosis and a high index of suspicion should be maintained in a cirrhotic patient with lymphocytic ascites.