TNF and histiocytic sarcoma: Adalimumab, an antagonist of TNF (Tumor Necrosis Factor)-α, is the only approved biologic drug for moderate-to-severe HS, with a significant improvement ranging from 41.8% to 77% of treated patients, as shown in clinical trials and real-life observational studies [33]; the evidence of a “window of opportunity” supports the early use of adalimumab in HS to ensure better clinical response [34].