Background: Primary bone marrow lymphoma (PBML) is a very uncommon neoplasm originally arising in the bone marrow system, and the most common pathological type is diffuse large B-cell lymphoma. 
Patients and methods: To describe the clinical characteristics of PBML and evaluate the risk factors related to prognosis, we recruited and studied 66 patients from our center and the current published literature. Various symptoms are present at the onset of PBML, the most important of which is cytopenia, followed by fever. Forty-seven of these patients were included in our analysis. 
Results: Univariate analysis suggested that B symptoms (P =0.024), a low serum platelet level (<75×10⁹/L; P =0.032), an elevated serum LDH level (P =0.039), and not achieving a complete response (CR) following initial therapy (P =0.007) are associated with worse outcomes. Multivariate analysis showed that only a low serum platelet level (<75×10⁹/L), B symptoms, and not achieving a CR following initial therapy are independent factors for prognosis. In addition, intensive regimens appear to be beneficial for prognosis. 
Conclusion: PBML is a lymphoma with special clinical features, and its recognition is important for establishing a definitive prognosis model and searching for appropriate therapy.
Keywords: diffuse large B-cell lymphoma, primary bone marrow lymphoma, bone marrow, B symptoms, cytopenia