Almost 70% of myelomas express CD56 (left panel); however, almost 80% of plasma cell leukemias are negative for this marker. Besides CD56, other aberrantly expressed antigens (in decreasing order of frequency) include CD117 (right panel), CD20, CD52, and CD10. CD19 is usually negative. Note the strong expression of CD38 in both panels. Image courtesy of: Genevieve Crane, MD, PhD, Johns Hopkins Hospital, Baltimore, Maryland, USA.