Gene Expression Profiling reveals a close relationship between Follicular lymphoma Grade 3A and 3B, but distinct profiles of Follicular Lymphoma Grade 1 and 2

Since follicular lymphoma (FL) grade 3A often coexist with a FL1/2 component a linear progression model of FL1, FL2 and FL3A has been developed. FL3B, on the other hand, is supposed to be more closely related to diffuse large B-cell lymphoma (DLBCL) and both FL3B and DLBCL are often simultaneously present in one tumor (DLBCL/FL3B). To obtain more detailed insight into FL progression, comprehensive analysis of a well-defined set of FL1/2 (n=22), FL3A (n=16), FL3B (n=6), DLBCL/FL3B (n=9) and DLBCL (n=45) was performed using gene expression profiling, immunohistochemical staining and genetic analysis by fluorescence in situ hybridization (FISH). 36 follicular lymphoma samples were hybridized to HGU133A Affymetrix GeneChips. In addition, this study contains 99 already published samples whereas 51 of them contribute to GSE4475, 36 contribute to GSE22470, 9 to GSE44164 and 3 to GSE48097. No re-normalisation of published samples was performed.