Immunophenotypic characteristics of plasma cells in <scp>POEMS</scp> syndrome

To analyze the immunophenotypic characteristics of plasma cells in patients with polyneuropathy, organomegaly, endocrinopathy, myeloma protein, and skin changes (POEMS) syndrome. This retrospective study included patients with POEMS syndrome hospitalized in the Department of Hematology, Huashan Hospital, from September 2017 to August 2025. Demographic data, clinical features, flow cytometry results, and bone marrow morphological findings were analyzed. A total of 69 POEMS syndrome patients (44 males, 25 females; median age 54 years) were included. Flow cytometry detected monoclonal plasma cells in 63.77% (44/69) of patients, with higher plasma cell proportions in cases with detectable monoclonal plasma cells group (p = 0.003). The nine-color flow cytometry protocol demonstrated a significantly higher detection rate of monoclonal plasma cells compared to the six-color protocol (77.42% vs. 52.63%, p = 0.033). Immunophenotypic analysis revealed 100% expression of CD38 and CD138, with higher expression of CD27, CD28, CD117, and CD81 in POEMS patients compared to multiple myeloma patients (all p < 0.05). Bone marrow morphology showed higher plasma cell proportions in the abnormal group (p = 0.01). With additional fluorescent channels and enhanced detection sensitivity offering simultaneous analysis of multiple surface markers and intracellular light chains (κ/λ), nine-color flow cytometry enables more precise identification of abnormal plasma cells in POEMS syndrome based on distinct marker expression profiles. CD27, CD28, and CD117 are recommended as potential immunomarkers for flow cytometric analysis in POEMS syndrome.