A case report of Castleman disease variant of POEMS syndrome presenting with prominent polyserositis and renal impairment.

Background: POEMS syndrome is a rare hematologic disorder related to plasma cell dyscrasia. The Castleman disease variant of POEMS syndrome is extremely rare and often misdiagnosed. In this study, we aim to present a noteworthy case of POEMS syndrome mainly manifested as multiple pleural effusion and renal impairment without M protein. Case presentation: A 47-year-old woman was admitted to the hospital with a 7-month history of lower extremity edema and 3 months of abdominal distension. Computed tomography revealed poly-serosal effusion and hepatosplenomegaly, while ultrasound showed multiple superficial lymphadenopathies. Serum protein electrophoresis and bone biopsy indicated no evidence of monoclonal plasma cell proliferation. Pathological results obtained from lymph node biopsy revealed Castleman disease (CD). The patient was ultimately diagnosed with the Castleman disease variant of POEMS syndrome without M protein. Renal function gradually declined in the later stages of the disease. After transferring to another hospital, the patient received a VPD chemotherapy regimen (Pomalidomide, Bortezomib, and Dexamethasone) and hemodialysis. Effusions in multiple serosal cavities were reduced, and renal function improved significantly following active treatment. Conclusion: POEMS syndrome without M protein is often misdiagnosed as other conditions. In patients presenting with multiple systemic manifestations, the possibility of POEMS syndrome or CD should be considered.