Coexistence of myeloproliferative neoplasms with multiple myeloma

Managing Editor:Peng Lyu Edited by:Lili Wang and Peng Lyu Myeloproliferative neoplasms(MPNs),including polycythemia vera(PV),essential thrombocythemia(ET),and primary myelofibrosis,originate from pluripotent hematopoietic stem cells and are characterized by the clonal proliferation of one or more peripheral blood lineages,often accompanied by hepatosplenomegaly,thrombosis,and extramedullary hematopoiesis.1 Multiple myeloma(MM)is a plasma cell(PC)malignancy of terminally differentiated B lymphocytes.2 The co-occurrence of MM and MPN is rare.There are a few reports of ET co-occurring with MM,3–5 with MM manifesting simultaneously with or several years after ET.PV combined with MM is much rarer;in most cases,MM manifests a few years after PV,and only nine cases of PV occurring simultaneously with MM have been reported.6 There is no standard treatment protocol for MM combined with MPN.Here,we report two cases of MPN co-occurring with MM after several years of hydroxyurea treatment to provide a clinical reference.