ALK and primary effusion lymphoma: The differential diagnosis of lymphomas sharing features of plasma cell differentiation should take into consideration aggressive diseases such as PBL, plasmablastic myeloma (PM), PEL, EC-PEL, ALK-positive LBCL, Burkitt lymphoma (BL), HHV8-positive DLBCL and EBV-positive DLBCL, NOS [1,2].