Mantle cell lymphoma and chronic lymphocytic leukemia: report of a rare disease association and review of the literature

We report the case of an 86-year-old female who presented with lymphadenopathy, lymphocytosis, and thrombocytopenia. Peripheral blood immunophenotypic analysis identified two lymphoid B cell populations that differ in CD23, CD200, and CD43 expression and in the intensity of CD5, CD20, CD79b, and kappa light chain. By fluorescence in situ hybridization (FISH) analysis, approximately 30% of the mononuclear cells were positive for the t(11;14)(q13;q32) and 40% for trisomy 12; analysis of the two populations separated by fluorescence activated cell sorting showed that t(11;14) occurs exclusively in CD23−/CD200−/CD43− cells and trisomy 12 in the CD23+/CD200+/CD43+ population. Lymph node biopsy showed a typical small lymphocytic lymphoma morphology, with an effaced architecture and a predominantly diffuse proliferation of small to medium-sized lymphoid cells and pseudo-follicles with the characteristic features of proliferation centers. In addition, a different type of randomly dispersed nodules was present, composed of cells slightly larger than the monomorphic lymphocytic proliferation that occupied most of the lymph node. Staining for Cyclin D1 and FISH for CCND1 showed protein expression and gene breaks restricted to these areas. Conventional cytogenetic analysis revealed two separate clones, one with trisomy 12 and the other with t(11;14)(q13;q32), both as unique clonal abnormalities. IGH analysis supports the presence of two populations with a different clonal origin. Taken together, these results provide strong evidence for the presence of a composite small lymphocytic lymphoma/chronic lymphocytic leukemia and mantle cell lymphoma. This association has been described in very rare cases that we briefly review.