PAX5 and neoplasm: Immunohistochemical staining of the pleural and pericardial effusions showed tumor cells positive for CD20, CD10 (approximately 10%), Mum-1 (approximately 80%), Bcl-2 (approximately 10%), CD79α, PAX-5, CD138, and C-myc (approximately 75%), and negative for CD21, CD38, HHV8, CD30, CD5, CD3, CK-pan, TTF1, Syn, CgA, and CD56.