From the archives of MD Anderson Cancer Center: Composite mantle cell lymphoma and lymphoplasmacytic lymphoma involving bone marrow at presentation.

Composite lymphoma, defined as two or more distinct well-defined entities involving the same anatomic site, is rare. Here we report a 79-year-old woman with composite mantle cell lymphoma (MCL) and lymphoplasmacytic lymphoma (LPL) involving bone marrow at the time of initial diagnosis. The patient presented with splenomegaly and lymphadenopathy and laboratory studies showed an elevated serum IgM level and IgM kappa paraprotein. Bone marrow evaluation showed concurrent involvement by MCL and LPL, supported by immunophenotypic studies that revealed two distinct aberrant B-cell populations. Next-generation sequencing analysis identified concurrent MYD88 and CXCR4 mutations and fluorescence in-situ hybridization showed CCND1 translocation, supporting the diagnosis of concomitant MCL and LPL. In conclusion, composite lymphoma can present in the bone marrow. The use of ancillary studies was essential in reaching the diagnosis in this case, as the results excluded the possibility of MCL lymphoma with plasmacytic differentiation, as well as other CD5- and CD10-negative small B-cell lymphomas.