A Case of Metastatic Signet Ring Cell Carcinoma Presenting as Tuberculous Peritonitis in an HIV/HCV Coinfected Patient

Abstract

Purpose: New onset ascites is most commonly due to chronic liver disease, but infectious and malignant causes must also be considered. This is a case of new onset ascites due to metastatic gastric signet cell adenocarcinoma in a patient with chronic hepatitis C and HIV coinfection. Case: A 59-year-old male with HIV (CD4 54) and chronic hepatitis C presented with abdominal pain, nausea, weight loss, and increasing abdominal girth for 2 months. Physical exam revealed bulging flanks with fluid wave and dullness to percussion. Laboratory findings were significant for hypoalbuminemia, absence of transaminitis, or thrombocytopenia, and elevated INR. PPD and Quantiferon-TB tests were negative. Right upper quadrant ultrasound with vascular dopplers did not show cirrhotic features or vascular thrombus. Abdominal CT was negative for intraabdominal organ abnormality. Diagnostic and therapeutic paracentesis revealed a low serum albumin-ascites albumin gradient (SAAG) and high WBC count with monocytic predominance. Peritoneal fluid was tested for cytology, acid-fast bacilli smear, culture, and gram stain, which were all negative. Repeat diagnostic and therapeutic paracentesis again revealed a low SAAG, and adenosine deaminase (ADA) testing was elevated at 26.3 IU/mL. The patient underwent a diagnostic laparoscopy with peritoneal biopsy. On laparoscopy, innumerable peritoneal lesions were noted, grossly resembling tuberculous seeding of the peritoneum. The presumed diagnosis of tuberculosis peritonitis was made and anti-tuberculin therapy was initiated. The following day, pathology from the peritoneal biopsy specimen returned as metastatic signet cell adenocarcinoma. An esophagoduodenoscopy was performed revealing a large, firm ulcerated tumor in the greater curvature of the gastric body. Pathology was consistent with diffuse signet ring cell carcinoma. Conclusion: As demonstrated by a recent meta-analysis, the ADA test has a high sensitivity and high specificity for revealing tuberculous peritonitis in ascitic fluid. This case underscores the importance of the ADA pre-test probability and of confirming the diagnosis with peritoneal biopsy, as malignancy may also present with high ADA levels.Figure: Ulcerated gastric mass, greater curvature.