Macrophages are known to be active in phagocytosis of necrotic/apoptotic tumour tissue, but additionally, recent findings suggest that TAMs present in ESFTs might differentiate by RANKL- and TNF-α-dependent mechanism to osteoclasts, which in turn participate in the bone resorption as a pathogenic mechanism of tumour osteolysis [19]. The gene discussed is TNFSF11; the disease is neoplasm.