ALK and primary effusion lymphoma: Recent studies have demonstrated that CD20-negative DLBCL is frequently restricted to a few variant subtypes of DLBCL with plasmablastic features and terminal B-cell differentiation, including plasmablastic lymphoma (PBL) of the oral mucosa type, PBL with plasmacytic differentiation, primary effusion lymphoma (PEL), Kaposi’s sarcoma-associated herpes virus (KSHV)-positive solid lymphoma/extracavitary PEL/HHV-8 associated DLBCL, and ALK-positive DLBCL [8-14].