[Clinical features of three cases with primary bone marrow lymphoma]

Primary bone marrow lymphoma (PBML) is a malignant lymphoma characterized by proliferation of lymphoma cells exclusively in the bone marrow without lymphadenopathy. Despite the dismal prognosis of PBML, it is a very rare lymphoma with limited evidence concerning its pathophysiology, making accumulation of cases important. We herein report three cases of PBML at our institution. The first patient was an 80-year-old man who presented with hemophagocytic syndrome and pancytopenia at admission, and died of septic shock during initial chemotherapy. The second patient was a 64-year-old man who achieved complete remission with intensive chemotherapies, but relapsed shortly after completing the final chemotherapy course. The third patient was a 66-year-old woman who underwent chemotherapies and allogeneic hematopoietic stem cell transplantation, only to relapse shortly after transplantation. Although early intervention with chemotherapy is essential for PBML treatment, diagnosis of PBML is very challenging due to the absence of lymph node involvement. Moreover, treatment outcomes of existing chemotherapy and transplantation therapies for PBML are still poor. Further accumulation of cases and development of new treatment strategies are desirable.