Bone marrow infiltration by flow cytometry at diffuse large B‐cell lymphoma NOS diagnosis implies worse prognosis without considering bone marrow histology

BACKGROUND The significance of discrepant findings between histology (BMB) and flow cytometry (FC) in bone marrow (BM) examination at diffuse large B-cell lymphoma (DLBCL) diagnosis is uncertain. METHODS We performed a 5-year retrospective single-center study of patients diagnosed by DLBCL not otherwise specified (n = 82), divided into three groups according to BM infiltration at diagnosis: BMB-/FC- (75.6%), BMB+/FC+ (13.4%), and BMB-/FC+ (11%). RESULTS Median infiltration by FC analysis of the BMB-/FC+ group was 0.8% and if we considered BM infiltration as positive in all cases, 4/9 would be upstaged. Median follow was 33 months. Event-free survival (EFS) after 18 months was 82, 23, and 27% for BMB-/FC-, BMB-/FC+, and BMB+/FC+, respectively (p