TNF and neoplasm: After conducting immunohistochemical studies, the authors suggested that neoplastic cells mediate this process by secreting a subset of osteoclast-stimulating cytokines, namely interleukin (IL) -1, IL-6 and tumor necrosis factor (TNF) -α, causing increased local bone resorption and, consequently, the formation of penetrating channels through the cortex, which allow for the tumor cells to escape the intramedullary space and spread to the surrounding soft tissues without extensive cortical destruction.