Synovitis, acne, pustulosis, hyperostosis, and osteitis syndrome: review and update

Abstract

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a spectrum of heterogeneous diseases characterized by osteoarticular and dermatological manifestations. Osteitis and hyperostosis are core clinical manifestations in SAPHO syndrome, typically affecting multiple areas and possibly progressing to irreversible osteoarticular damage. Most patients with SAPHO have cutaneous involvement, mainly manifested as palmoplantar pustulosis and severe acne. Systemic manifestations are uncommon but occasionally reported. Epidemiological studies suggest the annual prevalence of SAPHO syndrome varies from 0.00144 in 100,000 in Japanese individuals to fewer than 1 in 10,000 in White individuals. The precise etiopathogenesis of SAPHO remains unclear, but it is generally considered an autoinflammatory syndrome that may be related to various etiologies, such as immune dysfunction, infection and genetic predisposition. Owing to the relapsing-remitting disease course, the goal of management is to improve clinical symptoms and prevent disease progression. Various treatments, including nonsteroidal anti-inflammatory drugs, conventional disease-modifying antirheumatic drugs, bisphosphonates, biologics, and antibiotics, are promising options for alleviating the disease.

Keywords: SAPHO syndrome; diagnosis; etiology; imaging; treatment.

Figure 1.

Characteristic cutaneous manifestations of SAPHO syndrome: (a) palmoplantar pustulosis (PPP); (b) severe acne (SA). SAPHO, synovitis, acne, pustulosis, hyperostosis, and osteitis.

Figure 2.

Characteristic radiological manifestations of SAPHO syndrome. CT revealed bone cortical destruction and osteosclerosis of bilateral sternoclavicular joints, and swelling of the surrounding soft tissues (a). Whole spinal CT showed bone destruction in multiple vertebrae (b). MRI demonstrated multiple patchy, short T1 and long T2 (d) signals of lumbar vertebrae. WBBS showed increased radioactivity in the left sternoclavicular joint, the left first anterior rib, the second and fourth lumbar vertebrae, and the right iliac joint (e). PET/CT showed bone destruction and increased glucose metabolism in left clavicle bone (f) and vertebra (g). CT, computed tomography; MRI, magnetic resonance imaging; PET, positron emission tomography; SAPHO, synovitis, acne, pustulosis, hyperostosis and osteitis; WBBS, whole-body bone scintigraphy.