Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome - A challenging diagnosis not to be missed

SAPHO syndrome manifests as chronic inflammation of bones and joints, which may or may not be accompanied by skin changes. The term SAPHO is an acronym that stands for synovitis, acne, pustulosis (usually palmoplantar), hyperostosis and osteitis. The bones most commonly affected are those in the anterior chest wall (mainly the sternum, clavicles and sternocostoclavicular joints), the vertebrae and the sacroiliac joints, but peripheral and flat bones may also be involved, especially in children. There are no validated diagnostic criteria for SAPHO, and diagnosis is based on clinical and radiological findings. One of the main challenges in diagnosis is that the clinical features may occur many years apart. Additionally, patients may not develop all manifestations. Delayed diagnosis, as a result of a lack of awareness of SAPHO, can lead to patients suffering ongoing pain and disfiguring skin manifestations. One theory is that Propionibacterium acnes (isolated from bone biopsies in many SAPHO patients) triggers an auto-immune mediated chronic inflammation in genetically predisposed individuals. Treatment involves the use of nonsteroidal anti-inflammatory drugs, intra-articular steroids, bisphosphonates and biologicals. The course of SAPHO is often prolonged but, despite the challenges in diagnosis and treatment, the long-term prognosis is good.