Objective  To investigate the clinical features and treatment efficacy of bi-clonal lymphoplasmacytic lymphoma (LPL).

  Methods  We collected clinical data from five patients with bi-clonal LPL who visited Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College from 1993 to 2017 and reviewed the relevant literature.

  Results  Four of the five patients were male, and three were high-risk patients according to ISSWM staging. Bi-clonal serum immunofixation electrophoresis was performed. Abnormal lymphocytes and plasma cell infiltration were observed in the bone marrow of all five patients. Additionally, four patients expressed IgG and IgM antibodies, while three patients expressed different types of light chains. Serum immunofixation electrophoresis was biclonal in all five patients, and abnormal lymphocytes and plasma cell infiltration were observed in the bone marrow of all five patients. After bi-clonal LPL was confirmed in all patients, varied treatment strategies were employed. Two CD20-positive patients received rituximab-based chemotherapy regimens, one was treated with ibrutinib, one was treated with TCD because of the poor effect of bendamustine, and one was treated with M2. Four of the five patients achieved minimal response (MR) or greater. After a median follow-up time of 44.1 months, a median progression-free survival (mPFS) of 52.4 months, and a median overall survival (mOS) of 52.4 months were observed. At the end of the follow-up, two patients maintained partial response (PR) while two passed away.

  Conclusions  Occurrence of bi-clonal LPL is very rare, and deep and consistent understanding of the clinical features, diagnosis, treatment regression, and prognosis of this disease is lacking. Therefore, more summary and analysis of clinical cases is required.