CD20-negative diffuse large B-cell lymphomas: biology and emerging therapeutic options

CD20-negative diffuse large B-cell lymphoma (DLBCL) is a rare and heterogeneous group of lymphoproliferative disorders. Known variants of CD20-negative DLBCL include plasmablastic lymphoma, primary effusion lymphoma, large B-cell lymphoma arising in human herpesvirus 8-associated multicentric Castleman disease and anaplastic lymphoma kinase-positive DLBCL. Given the lack of CD20 expression, atypical cellular morphology and aggressive clinical behavior characterized by chemotherapy resistance and inferior survival rates, CD20-negative DLBCL represents a challenge from the diagnostic and therapeutic perspectives. The goals of the present review are to summarize the current knowledge on the biology of the distinct variants of CD20-negative DLBCL, provide future therapeutic directions based on the limited preclinical and clinical data available, and increase awareness concerning these rare malignancies among pathologists and clinicians.