 Prior diagnosis of plasma cell lymphoma (i.e.multiple myeloma or plasmacytoma), the presence of lytic bone lesions, increased levels of serum calcium, renal insufficiency, and anemia, and the presence of a myeloma protein in the serum and/or urine favor the diagnosis of plasmablastic plasma cell lymphoma rather than plasmablastic lymphoma.Ultimately, however, the marker proteins expressed by the plasmablastic cells in the two diseases are almost identical and a diagnosis of "plasmablastic neoplasm, consistent with PBL or multiple myeloma" may be acceptable in some cases according to the current World Health Organization classification.