OBJECTIVETo report the diagnosis, differential diagnosis and treatment of three rare cases of primary bone marrow diffuse large B cell lymphoma (DLBCL), and to improve the recognition of this disease.

METHODSThe clinical characteristics, therapeutic course and the outcome of these patients were reviewed. Meanwhile, a series of examinations including morphology, flow cytometry, immunohistochemistry and molecular biology of bone marrow samples were also performed.

RESULTSThese three patients who were old at the onset age (56, 60 and 70 years old), primarily revealed as abnormal blood count and experienced an aggressive course of disease. Physical and imaging examination showed no enlargement of lymph node, liver and spleen, the patients were finally diagnosed as primary bone marrow DLBCL by bone marrow morphology, flow cytometry and immunohistochemistry analyses. They were treated with rituximab combined chemotherapy, which achieved a complete response, but still need longer follow-up to further evaluate their survival.

CONCLUSIONPrimary bone marrow DLBCL was encountered rarely in clinical practice, and this is the first report in China. Further investigation of pathogenesis and therapeutic strategies of this rare disease was warranted.