Follicular dendritic cell tumor of the spleen associated with diffuse large B-cell lymphoma.

We report the case of a 50-year-old woman with an isolated large mass of the lower pole of the spleen. Splenectomy was performed and revealed a follicular dendritic cell (FDC) tumor associated with diffuse large cell lymphoma. Dendritic cells were CD21(+), CD35(+), CNA42(+), CD20(-), and Epstein-Barr virus (EBV)(+). They contained a clonal EBV genome as shown by polymerase chain reaction analysis of the LMP-1 gene polymorphism. Interestingly, the lymphoma cells were intermingled with the neoplastic FDCs and displayed a germinal center cell phenotype (CD20(+), CD10(+), Bcl2(+), and EBV(-)). Double staining confirmed that EBV was restricted to the FDCs. Clinical, radiologic, and pathologic staging showed no other lymphoma localization. To the best of our knowledge, this association has never been reported. Based on the well-established role of FDCs in B-cell survival and proliferation, this observation suggests that the FDC tumor represented a favorable microenvironment for lymphoma cells with germinal center phenotype.