Molecular and immunological dissection of diffuse large B cell lymphoma: CD5+, and CD5- with CD10+ groups may constitute clinically relevant subtypes.

Diffuse large B cell lymphoma (DLBL) constitutes the greatest percentage of adult non-Hodgkin's lymphomas and represents a diverse spectrum of lymphoid neoplasms. Clinicopathologic, phenotypic and genotypic findings were correlated and compared for 63 DLBL cases to investigate whether they represent clinically relevant subtypes. They were all cyclin D1 negative and were phenotypically divided into three groups, ie group I (CD5+ type, n=11), group II (CD5- CD10+ type, n=19), and group III (CD5- CD10- type, n=33). Data were correlated by observing the respective gene rearrangement and expression of BCL2 and BCL6. In clinical aspects, the group I cases demonstrated a significantly inferior survival than those of the other two groups (log-rank test, P = 0.016). Although rearrangement of BCL2 and BCL6 did not show any inclination to a specific subgroup, the immunohistochemical detection of BCL2 was less frequent, at a statistically significant level (P=0.011), in group II (50%) than in group I (82%) and III (82%) cases. This appears to confirm the unique aspect of the CD5- CD10+ type DLBL, indicating a certain relationship with the normal germinal center cells which usually lack BCL2 expression. The BCL6 protein expression was detected in most of the present DLBL cases (92%) irrespective of this grouping. These data suggest that the phenotypic delineation by the detection of CD5 and CD10 will improve our understanding of DLBL and be helpful in a future subgrouping of DLBL.