ALK and primary effusion lymphoma: Such differential diagnostic considerations include anaplastic (or pleomorphic) plasma cell myeloma, extramedullary plasmacytoma (anaplastic, plasmablastic, and plasmacytic), DLBCL with plasmacytoid differentiation, anaplastic lymphoma kinase (ALK)-positive large B cell lymphoma, extracavitary or solid variant of primary effusion lymphoma (PEL), DLBCL associated with HHV8-positive multicentric Castleman disease, and EBV-positive plasmacytoma in immunocompetent patients (EPIC).