Distinct Clinical Features of Plasma Cell Myeloma Patients Exhibiting Dysmorphic Plasma Cells: Association with More Plasma Cells at Diagnosis

Dysmorphic plasma cells are occasionally found in bone marrow (BM) aspirates of plasma cell myeloma (PCM) patients. We retrospectively analyzed the incidences of significant dysmorphic plasma cells (SDPC) presentations and their associations with clinical features in PCM patients. Total 91 PCM patients diagnosed from January 2013 to December 2017 at author's institution were enrolled. SDPC presentation was determined as ≥ 5% (SDPC5) or ≥ 10% (SDPC10) among total PC and clinical features of PCM patients were compared with respect to SDPC presentation status. Incidence of SDPC5/SDPC10 presentation was 39.6%/18.7%. Patients with SDPC5/SDPC10 showed significantly more BM PC ( P  = 0.004/0.020) and higher incidences of CKS1B gains ( P  = 0.022/0.001) and RB1 loss ( P  = 0.032 for SDPC10 only) at diagnosis than those without SDPC5/SDPC10. Patients with SDPC5/SDPC10 also showed significantly greater absolute BM PC ( P =  0.007/0.034 and 0.047/0.049 for 1st and 2nd follow-up, respectively) and serum M-protein ( P =  0.041/0.044 and 0.039/0.049 for 1st and 2nd follow-up, respectively) reductions after chemotherapy than those without SDPC5/SDPC10. SDPC5/SDPC10 presentation was confirmed as an independent predictor of BM PC ≥ 37.7% [hazard ratio (HR) 4.649/2.613, P  = 0.005/0.039]. Our present study demonstrated that SDPC presentation would be an independent predictor of more BM PC at diagnosis in PCM patients. Associations between SDPC presentation and higher incidence of CKS1B gains and RB1 loss, greater PC/serum monoclonal protein reductions after chemotherapy were also identified. Association between SDPC presentation and favorable treatment response should be evaluated in more comprehensive study.