CD19 and B-cell neoplasm: The aim of the present study was to compare the findings of interphase FISH analysis performed on CD19‐selected cells (CD19S FISH) with those of FISH performed on non‐selected cells (NS FISH), and also compare the results with concurrent FC analysis (routine and MRD FC) and molecular polymerase chain reaction (PCR) analysis in various types of mature and immature CD19‐positive B‐cell neoplasms.