Differentiating Burkitt and Diffuse Large B-cell Lymphoma
Differentiating Burkitt and Diffuse Large B-cell Lymphoma
The FL cases had the smallest cells by FSC, demonstrated markedly lower MFIs for all markers with the exception of CD10, and the %CD71 for FL was very low (3%) Table 2. Of note, the FHyp cells were more intermediate in average cell size and demonstrated slightly higher %CD71 than FL. The CD10– DLBCL cases demonstrated large cells by FSC and higher proliferation than the other 2 aforementioned control groups (CD71 MFI and %CD71). Based on our laboratory's experience, the general patterns seen in these groups had the immunophenotypic findings expected from the literature, demonstrating that the gating strategies used in this study produced reliable results.
The 9 parameters measured showed significant variability (as evidenced by the high SDs) within several groups, particularly CD10+ DLBCL and CD10– DLBCL, demonstrating that these are indeed heterogeneous entities. The FL, FHyp, and BL groups demonstrated lower SDs, suggesting less intercase variability in these entities. Because of the amount of variance seen, statistically significant differences between BL and DLBCL (CD10+ and CD10– subgroups in total) were not seen for all parameters. However, several important differences between the groups of interest, BL and CD10+ DLBCL, were found Figure 1.
(Enlarge Image)
Figure 1.
Graphs for each parameter for Burkitt lymphoma (gray bars) and CD10+ diffuse large B-cell lymphoma (white bars) cases demonstrate significant differences for FSC, CD10, CD79b, CD43, and %CD71. The large intergroup variance is evidenced by the large SD bars. FSC-H, forward scatter height; MFI, mean fluorescence intensity; SSC-H, side scatter height.
As expected, the FSC was lower for BL than for CD10+ DLBCL (P = .01), reflecting the typically smaller size of the BL cells. The CD43 MFIs were brighter in BL than in CD10+ DLBCL (P = .029), and the CD79b MFI was significantly lower in the BL group (P = .016). CD10 was significantly higher in BL (P = .029). With an average of 69% of cells expressing CD71, BL had the highest %CD71 of any group, and this %CD71 was significantly higher than in the CD10+ DLBCL group (P = .020). In addition, the MFIs for CD71 tended to be higher in BL than in CD10+ DLBCL, but were not significant (P = .054). Since CD71 can act as a surrogate marker of proliferation, these results mirror the results of the MIB-1/immunohistochemical study, which showed a nearly 100% proliferation index. No statistically significant differences between BL and CD10+ DLBCL were seen in our data set for SSC, CD20, and CD38.
The 5-point scoring system described was applied to 10 of 19 total BL cases, 10 of 12 total CD10+ DLBCL cases, and 5 of 8 total CD10– DLBCL cases. Samples were scored only if they had all 5 parameters available for evaluation. The results of the scoring system showed that 6 (60%) of 10 BL cases had a score of 3 or greater. In contrast, only 1 (10%) of the 10 CD10+ DLBCL cases had a score of 3, and none of the 5 CD10– DLBCL cases had a score of 3 or more. The χ analysis of these results indicated that a score of 3 or more was significantly associated with BL (BL vs CD10+ DLBCL, 6/10 vs 1/10; P = .04; χ test; and BL vs all DLBCL, 6/10 vs 1/15; P = .01). Representative examples of BL and CD10+ DLBCL cases are shown in Image 2. Of note, the single case of BCLU with rearrangements of c-MYC and BCL2 had a score of 1, suggesting that the coexisting BCL2 rearrangement may have changed the overall immunophenotyping pattern of neoplastic cells.
(Enlarge Image)
Image 2.
Mean fluorescent intensity (MFI) for 5 parameters in representative cases of Burkitt lymphoma (A) and CD10+ diffuse large B-cell lymphoma (B). FITC, fluorescein isothiocyanate; FSC-H, forward scatter height; PE, phycoerythrin; SSC-H, side scatter height.
Results
FC Analysis Using Nine Parameters
The FL cases had the smallest cells by FSC, demonstrated markedly lower MFIs for all markers with the exception of CD10, and the %CD71 for FL was very low (3%) Table 2. Of note, the FHyp cells were more intermediate in average cell size and demonstrated slightly higher %CD71 than FL. The CD10– DLBCL cases demonstrated large cells by FSC and higher proliferation than the other 2 aforementioned control groups (CD71 MFI and %CD71). Based on our laboratory's experience, the general patterns seen in these groups had the immunophenotypic findings expected from the literature, demonstrating that the gating strategies used in this study produced reliable results.
The 9 parameters measured showed significant variability (as evidenced by the high SDs) within several groups, particularly CD10+ DLBCL and CD10– DLBCL, demonstrating that these are indeed heterogeneous entities. The FL, FHyp, and BL groups demonstrated lower SDs, suggesting less intercase variability in these entities. Because of the amount of variance seen, statistically significant differences between BL and DLBCL (CD10+ and CD10– subgroups in total) were not seen for all parameters. However, several important differences between the groups of interest, BL and CD10+ DLBCL, were found Figure 1.
(Enlarge Image)
Figure 1.
Graphs for each parameter for Burkitt lymphoma (gray bars) and CD10+ diffuse large B-cell lymphoma (white bars) cases demonstrate significant differences for FSC, CD10, CD79b, CD43, and %CD71. The large intergroup variance is evidenced by the large SD bars. FSC-H, forward scatter height; MFI, mean fluorescence intensity; SSC-H, side scatter height.
As expected, the FSC was lower for BL than for CD10+ DLBCL (P = .01), reflecting the typically smaller size of the BL cells. The CD43 MFIs were brighter in BL than in CD10+ DLBCL (P = .029), and the CD79b MFI was significantly lower in the BL group (P = .016). CD10 was significantly higher in BL (P = .029). With an average of 69% of cells expressing CD71, BL had the highest %CD71 of any group, and this %CD71 was significantly higher than in the CD10+ DLBCL group (P = .020). In addition, the MFIs for CD71 tended to be higher in BL than in CD10+ DLBCL, but were not significant (P = .054). Since CD71 can act as a surrogate marker of proliferation, these results mirror the results of the MIB-1/immunohistochemical study, which showed a nearly 100% proliferation index. No statistically significant differences between BL and CD10+ DLBCL were seen in our data set for SSC, CD20, and CD38.
Results of the Scoring System
The 5-point scoring system described was applied to 10 of 19 total BL cases, 10 of 12 total CD10+ DLBCL cases, and 5 of 8 total CD10– DLBCL cases. Samples were scored only if they had all 5 parameters available for evaluation. The results of the scoring system showed that 6 (60%) of 10 BL cases had a score of 3 or greater. In contrast, only 1 (10%) of the 10 CD10+ DLBCL cases had a score of 3, and none of the 5 CD10– DLBCL cases had a score of 3 or more. The χ analysis of these results indicated that a score of 3 or more was significantly associated with BL (BL vs CD10+ DLBCL, 6/10 vs 1/10; P = .04; χ test; and BL vs all DLBCL, 6/10 vs 1/15; P = .01). Representative examples of BL and CD10+ DLBCL cases are shown in Image 2. Of note, the single case of BCLU with rearrangements of c-MYC and BCL2 had a score of 1, suggesting that the coexisting BCL2 rearrangement may have changed the overall immunophenotyping pattern of neoplastic cells.
(Enlarge Image)
Image 2.
Mean fluorescent intensity (MFI) for 5 parameters in representative cases of Burkitt lymphoma (A) and CD10+ diffuse large B-cell lymphoma (B). FITC, fluorescein isothiocyanate; FSC-H, forward scatter height; PE, phycoerythrin; SSC-H, side scatter height.