CD163 is useful in identifying cells of monocyte/macrophage lineage in normal and neoplastic conditions (1,2). This antibody reacts with human scavenger receptor cysteine-rich protein CD163 (p155, M130) found on mononuclear phagocytes including human monocytes and macrophages (1). Compared with the CD68 antibodies, studies have shown that CD163 demonstrated greater specificity as a marker of disorders of monocyte/macrophage origin (2). However, immunohistochemical evaluation of CD163 expression does not seem to be a sensitive means of determining monocytic differentiation of AMLs or myeloid sarcoma (3).