Purpose To investigate the diagnosis,differential diagnosis and clinical manifestation of primary plasma cell leukemia (PPCL) and lymphoma with increased plasma cell.Methods Through clinical data and cell morphology,flow cytometry (FCM),immunofixation electrophoresis and immunohistochemistry of EliVision two-step examination were used to analyze 7 cases of PPCL and 3 cases of lymphoma with increased plasma cell.Results All patients with PPCL and lymphoma with increased plasma cell presented with anemia,thrombocytopenia,fever,liver and spleen and lymph node swelling.The proportion of plasma cells in peripheral blood morphology were larger than 20％,accompanied by morphological abnormality.FCM of peripheral blood showed all 7 cases of PPCL expressed CD38 and CD138,CD56 expression in the 2 cases and CD20 in the 2 cases.The light chain (Lamda,Kappa) showed a monoclonal restricted expression,which was consistent with the diagnosis of PPCL.CD19 and CD45 were weakly positive in 3 cases of lymphoma with increased plasma cell,CD38 and CD138 were positive,and no restricted expression was found in light chain IgL,wich belonging to the immunophenotypes of normal plasma cells.Of 3 cases of light chain (Ig) without restrictive expression,2 of them were angioimmunoblastic T-cell lymphoma (ATCL) and 1 case was CD30-positive sinusoidal large B-cell lymphoma (CD30 + SLBCL) that confirmed by lymph node biopsy and pathological examination.Conclusion The PPCL and lymphoma with increased plasma cell have the same clinical manifestations and similar morphological characteristics of blood cells.The diagnosis of PPCL should be combined with immunoelectrophoresis and FCM,and the diagnosis of lymphoma with increased plasma cell needs to be confirmed by histological examination of lymph nodes.