S5890 Multicentric Castleman’s Disease: An Unusual Culprit for Portal Hypertension

Introduction: Castleman's disease (CD) is a heterogeneous group of rare lymphoproliferative disorders, with unicentric or multicentric involvement. Multicentric Castleman's disease (MCD), associated with elevated interleukin-6 (IL-6), is characterized by systemic symptoms and widespread lymphadenopathy. Ascites in MCD is rare and typically linked to lymphatic obstruction or increased vascular permeability. Portal hypertension secondary to cirrhosis in MCD patients without classic risk factors is exceedingly uncommon. Case Description/Methods: A 47-year-old woman with MCD (on siltuximab), chronic kidney disease stage 3B, and hypothyroidism presented with worsening abdominal distention and pain. She had previously undergone PleurX catheter placement for recurrent ascites, which was removed due to Serratia peritonitis. On presentation, she was afebrile and hemodynamically stable. Labs showed stable liver enzymes, normal international normalized ratio, and platelet count >150,000/μL. Ascitic fluid analysis revealed a serum-ascites albumin gradient (SAAG) >1.1 g/dL and total protein <2.5 g/dL, consistent with portal hypertension. Computed tomography imaging showed ascites, borderline hepatomegaly, and subtle liver nodularity concerning for cirrhosis. Liver Doppler ultrasound was unremarkable. She denied alcohol use, intravenous drug use, and had no known viral hepatitis exposure. Previous endoscopies showed no varices or signs of chronic liver disease. No clinical stigmata of liver dysfunction had been noted. Discussion: Ascites in MCD is uncommon and usually secondary to lymphatic obstruction or cytokine-mediated increased vascular permeability. In this case, recurrent ascites with imaging and fluid analysis suggested portal hypertension. The absence of classic risk factors such as alcohol, viral hepatitis, or metabolic liver disease makes this presentation rare. Cirrhosis in MCD has been rarely reported. Prior cases by Abarca et al. and Takai et al. have described portal hypertension without established cirrhosis, suggesting immune-mediated or cytokine-induced hepatic changes. Although siltuximab has not been definitively linked to liver fibrosis, data are limited. We present a rare case of presumed cirrhosis and portal hypertension in a patient with MCD. This underscores the need to consider hepatic involvement in MCD patients with unexplained ascites and suggests the value of longitudinal hepatic monitoring in this population.