Composite Diffuse Large B-cell and Mantle Cell Lymphoma: A Case Report

Composite lymphoma is an extremely rare clinical entity and is characterized by the presence of two different subtypes of lymphoma in the same lymph node. We report a case of composite lymphoma in a 57-year-old male presenting with leg and groin pain. The right inguinal lymph node biopsy showed large and small cells. Immunohistochemistry was consistent with large cells staining for diffuse large B-cell lymphoma (DLBCL) and small cells positive for mantle cell lymphoma (MCL). Polymerase chain reaction (PCR) analysis of immunoglobulin heavy (IGH) chain and immunoglobulin kappa (IGK) light chain gene rearrangements confirmed that the two were clonally unrelated neoplasms. There are only two reported cases of composite lymphoma with this combination in the published English literature. We report the third such case and discuss the pathology, diagnostic challenges and management of composite lymphoma.