TNF and histiocytic sarcoma: TNF-alpha, a cytokine predominantly synthesized by activated macrophages, is involved in a spectrum of biological activities, including the induction of pro-inflammatory events, stimulation of fibroblast growth, mediation of cytotoxic or cytostatic effects, activation of endothelial cells, and promotion of IL-8 synthesis [5,7] and is observed in the pathophysiology of HS.