S5413 POEMS Syndrome Complicated by Nodular Regenerative Hyperplasia and Non-Cirrhotic Portal Hypertension

Introduction: POEMS syndrome (Polyneuropathy, Organomegaly, Endocrinopathy, Monoclonal gammopathy, and Skin changes) is a rare multisystem disorder caused by an underlying plasma cell dyscrasia. While hepatic involvement is uncommon in POEMS syndrome, non-cirrhotic portal hypertension (NCPH) and nodular regenerative hyperplasia (NRH) has rarely been reported as a complication. We present a patient with POEMS syndrome complicated by NRH and ascites due to NCPH, who was successfully diagnosed and managed. Case Description/Methods: A 65-year-old man with POEMS syndrome diagnosed 20 years prior, treated with radiation and chemotherapy (lenalidomide, cyclophosphamide, dexamethasone), presented with new-onset large volume ascites. He was found to have acute kidney injury (creatinine 2.5 mg/dL). Ascitic fluid analysis revealed a serum-ascites albumin gradient >1.1 g/dL and total protein <2.5 g/dL consistent with portal hypertension. Imaging showed a nodular liver concerning for cirrhosis. Given lack of risk factors for liver disease, transjugular liver biopsy was performed which revealed a hepatic venous pressure gradient of 12 mmHg, with pathology showing regenerative nodules, preserved hepatic architecture and no significant fibrosis, consistent with NRH. Following volume expansion with intravenous albumin while holding diuretics, renal function improved. He had significant recurrent ascites requiring titration of diuretics and routine paracentesis. Discussion: While hepatomegaly is common in POEMS, idiopathic non-cirrhotic portal hypertension can rarely be a complication, with NRH described in 1 prior case thus far. NRH is an uncommon, benign hepatic pathology characterized by diffuse transformation of liver parenchyma into regenerative nodules without significant fibrosis. The proposed mechanism involves cytokine-mediated endothelial injury, driven by elevated vascular endothelial growth factor and pro-inflammatory markers, resulting in microvascular remodeling. While other cases of portal hypertension have occurred either before or closely after POEMS diagnosis, our patient presented 20 years after initial POEMS diagnosis. Notably, prior chemotherapy exposure may also increase risk for NRH. Distinguishing NCPH from cirrhosis is essential, as it influences management and prognosis. This case highlights the importance of clinicians maintaining a broad differential for ascites in patients with computed tomography findings suggestive of cirrhosis, and reinforces the role of liver biopsy in diagnosing NCPH when clinically suspected.