Negative Serum Ascites Albumin Gradient (SAAG) in the Setting of Cholangiocarcinoma: A Case Report

Ascites is the accumulation of fluid in the peritoneal cavity which leads to abdominal distention. Malignant ascites may occur in several tumor types including liver, pancreas, colon, breast, and ovary. Serum ascites albumin gradient (SAAG) is the difference between albumin in the serum and ascitic fluid. A SAAG greater or equal to 1.1 g/dL is characteristic of portal hypertension. A SAAG less than 1.1 g/dL can be seen in hypoalbuminemia, malignancy, or an infectious process. We report a rare case of malignant ascites in a 61-year-old female patient who presented with a chief complaint of abdominal pain with distention that was preceded by a 25-pound weight loss over the last three months. The patient underwent a paracentesis after a computed tomography (CT scan) revealed a heterogenous liver mass with associated ascites. Ascitic fluid analysis revealed a SAAG of -0.4 g/dL. CT-guided core needle biopsy of the hepatic mass revealed a poorly differentiated carcinoma with immunostaining suggestive of an underlying cholangiocarcinoma. Cholangiocarcinoma is an extremely uncommon etiology of acute new-onset ascites and has not been shown to produce high protein ascites with a negative SAAG. It is therefore important for clinicians to get ascitic fluid analysis in order to calculate a SAAG to help develop differential diagnosis for the cause of ascitic fluid buildup.