Investigate the significance of Royal Marsden Hospital(RMH) Immunophenotyping Score System in the diagnosis of chronic lymphocytic leukemia (CLL) of China, devote to achieve CLL′s diagnosis and differential diagnosis by flow cytometry.

Case-control study method was utilized to compare the diagnostic efficacy of 43 CLL patients and 43 B cell chronic lymphoproliferative disorders (B-CLPD, control group). These cases were collected during January 2015 to February 2017 in our laboratory. The samples were labeled by a series of monoclone antibodys, and all cells were definitely classified using CD45-SS gating. B cells could be easily gated from other cell clusters according to the surface expression of CD19. Then the B cell markers expression was analyzed to statistic the RMH score (CD5, CD23, FMC7, sIgM and CD22). Finally, the differences of RMH score and markers expression levels between CLL group and control group were acquired.

The RMH score between the two groups showed significantly difference (χ² =74.459, P<0.05). The expression levels of CD5, CD23, FMC7, sIgM and CD22 between the two groups all showed significantly difference (χ² =27.158, 33.907, 9.685, 12.452 and 11.417 respectively; P<0.05 or 0.001). However, there were still two special cases. The first was a case that tended to have CLL clinical manifestations and cell morphology, while the RMH score was only 3; and the seconed case was a case maintained low RMH score which is only 4, but the morphological characteristics and other inspections showed it was PLL. In addition, CD5 and CD22 showed no significantly difference between CLL and MCL(χ²=2.057, 0.813; P>0.05) ; CD10 usually expressed on FL; CD20 can distinguish CLL from MCL(χ²=5.816, P<0.05), but there was largely unhelpful in distinguishing between CLL and other subgroups. FMC7 showed statistical difference between CLL and FL, MCL, SMZL and CD5^-CD10^-subgroups(χ²=10.228, 7.984, 8.905, 13.478; P<0.01 or P<0.05). The difference was also seen between CLL and non-FL subgroup. sIgM can only be used to distinguish CLL from MCL and CD5^-CD10^-subgroups(χ²=8.441, 4.722; P<0.05).

In this study, 98% of CLL cases could be diagnosed by RMH Immunophenotyping score system, and could be differentiated from B-CLPD cases. In a few cases, it is necessary to combine the clinical and other examination results before making final diagnosis, as the other results, such as morphotogy, are inconsistent with flow cytometry resulots.