[Adult chronic nonbacterial osteitis : A uniform approach to a rare disease-Reported according to the consensus recommendations of an international expert committee 2025].

Adult chronic nonbacterial osteitis (CNO) is a rare autoinflammatory bone disease formerly described under heterogeneous terms, such as SAPHO (acronym for synovitis, acne, pustulosis, hyperostosis and osteitis) or sternocostoclavicular hyperostosis (SCCH). New international consensus recommendations now define adult CNO as a distinct nosological entity with osteitis as the obligatory hallmark. The disease typically presents as monofocal inflammation of the anterior chest wall; cutaneous manifestations are not obligatory. Overlaps with axial spondylarthritis (axSpA) or psoriatic arthritis (PsA) are recognized but uncommon (< 30% of cases). The diagnostics follow a structured algorithm involving clinical assessment, targeted laboratory diagnostics (including bone metabolism markers) and magnetic resonance imaging (MRI)-based imaging. Treatment decisions are based on the combined presence of clinical symptoms and radiological activity. A stepwise approach is recommended, starting with nonsteroidal anti-inflammatory drugs (NSAID), followed by intravenous bisphosphonates or tumor necrosis factor (TNF) alpha inhibitors in cases of insufficient response. Treatment monitoring should be carried out every 12 weeks. In stable remission, tapering or withdrawal can be considered. All specific therapies are performed off-label and require formal reimbursement approval. The management should be rheumatologically led and interdisciplinary. Lifestyle modifications, such as smoking cessation, physical activity and dental care during bisphosphonate therapy, are integral components. The new recommendations enable a clinically applicable, standardized management of this insufficiently defined disease.