Abstract: Objective To investigate the morphological and immunophenotypic features of the invasion in bone marrow in patients with diffuse large B-cell lymphoma (DLBCL) , and provide scientific basis for accurate diagnosis of bone marrow invasion by DLBCL cells. Methods From June 2014 to June 2019, samples of tumor tissues and peripheral blood of 59 cases of DLBCL were collected from the Fourth Hospital of the Hebei Medical University. The morphological and bone marrow pathological data, flow cytometry and fluorescent in situ hybridization analysis (FISH) features of the tumor cells of the patients with DLBCL were analyzed. Results In 59 cases of DLBCL patients with bone marrow invasion, the increased white blood cells, anemia and thrombocytopenia were found in the majority of these patients, and tumor cells were found in peripheral blood in 43 cases (72.88%). Bone marrow biopsy showed that the proportion of the lymphoma cells in bone marrow tissue ≥10％ was found in 31 patients (52.54%). The invasion pattern of the lymphoma cells was diffuse hyperplasia in the bone marrow, and hematopoietic tissue was significantly reduced or absent. The results of immunohistochemical staining and flow cytometry showed that CD20, CD19, CD79b and cCD79a were positively expressed in the lymphoma cells. HLA-DR,CD22, sIgM, CD43, CD10, FMC7 and CD123 expressions were found in some patients. CD38, TdT, CD103, CD25, CD3, CD2, MPO, CD33, CD13, CD7 and CD56 were negatively expressed in these cells. C-myc gene rearrangement was not observed in 12 patients detected by FISH. Conclusion Bone marrow morphology and pathology combined with immunophenotype detection are the important basis for accurate diagnosis of DLBCL.

Key words: lymphoma, large B-cell, diffuse, bone marrow examination, immunophenotyping