Primary central nervous system lymphoma: a clinicopathological study of 75 cases

SummaryAimsPathological and clinical data in a large series of immunocompetent patients with primary lymphoma of the central nervous system (PCNSL) were analysed.MethodsWe immunostained tumour specimens of 75 patients for CD3, CD4, CD5, CD8, CD10, CD20, CD30, CD79a, Bcl-2, Bcl-6, CD138, MUM1, TDT, PAX5, FOXP1 and Ki-67 and performed in situ hybridisation for Epstein-Barr virus (EBV) RNA. Eleven cases were investigated for rearrangements of BCL6, immunoglobulin heavy chain (IGH) and FOXP1 genes using fluorescent in situ hybridisation (FISH).ResultsHistologically, most cases were classified as diffuse large B-cell lymphoma (80.2%) predominantly of centroblas-tic type. Immunophenotypic profiling revealed that 96% and 4% of cases corresponded to non-germinal centre and germinal centre type, respectively. FISH analysis showed t(3;14)/IGH-BCL6 in 2/11 cases and trisomy 3 in 2/11 cases. FOXP1 rearrangements were not found. At survival analysis, Karnofsky index >80 and presence of Bcl-6 expression showed independent significant association with favourable patient outcome.ConclusionsPCNSL represents a histologically and immu- nophenotypically very homogeneous lymphoma type, probably derived from germinal centre exit B cells. The frequent overexpression of FOXP1 appears not to be related to FOXP1 gene rearrangement. Survival analyses disclosed Bcl-6 expression and high Karnofsky performance score as independent prognostic parameters associated with favourable outcome.