CD11b is a classical marker for all microglia and macrophage subtypes which is expressed in all regions of human brain.31 CD163 is usually found on perivascular macrophages in the normal brain25, 32, 33 but also on parenchymal microglia and macrophages in Alzheimer's and Parkinson's diseases34 and MS.25, 32 Here we found variable numbers of CD163+ and CD11b+ cells at perivascular sites and in the parenchyma of all but two patients (Table 1). The gene discussed is CD163; the disease is myeloid sarcoma.