Synovitis acne pustulosis hyperostosis osteitis

Synovitis Acne Pustulosis Hyperostosis Osteitis (SAPHO) syndrome is a rare disorder that involves a combination of skin and musculoskeletal conditions. The syndrome is characterized by synovitis (inflammation of the synovial membrane), severe acne, pustulosis (pustular skin eruptions), hyperostosis (abnormal bone growth), and osteitis (bone inflammation). SAPHO syndrome is considered part of the seronegative spondyloarthropathies, a group of disorders that affect the joints but are negative for rheumatoid factor, a common marker of rheumatoid arthritis.

Symptoms and Diagnosis

The symptoms of SAPHO syndrome can vary widely among individuals but typically include severe acne, often in the form of acne conglobata or acne fulminans, and pustular skin lesions. Musculoskeletal symptoms are also prominent and can include pain, swelling, and stiffness in the affected areas, most commonly the chest wall, spine, and long bones. The diagnosis of SAPHO syndrome is primarily clinical, based on the combination of skin and musculoskeletal symptoms. Imaging studies, such as X-rays and MRI, are used to identify characteristic features of bone involvement. Blood tests may show elevated markers of inflammation but are not definitive for the diagnosis.

Etiology and Pathogenesis

The exact cause of SAPHO syndrome remains unknown, but it is believed to involve a combination of genetic, immunologic, and infectious factors. The syndrome has been associated with the presence of Propionibacterium acnes, a common skin bacterium, in bone lesions, suggesting a possible infectious trigger. However, the role of this bacterium in the pathogenesis of SAPHO syndrome is still under investigation. There is also evidence to suggest a genetic predisposition to the syndrome, although no specific genes have been definitively linked to its development.

Treatment

Treatment of SAPHO syndrome focuses on managing symptoms and may include medications to reduce inflammation and pain, such as nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and disease-modifying antirheumatic drugs (DMARDs). In cases where Propionibacterium acnes is suspected to play a role, antibiotics may also be prescribed. For severe skin lesions, treatments may include systemic retinoids or biologic therapies targeting specific inflammatory pathways. Physical therapy can help maintain joint function and mobility.

Prognosis

The prognosis for individuals with SAPHO syndrome varies. While the syndrome can cause significant pain and disability, it is not life-threatening. The course of the disease is often chronic and relapsing, requiring long-term management. Some individuals may experience periods of remission, while others may have persistent symptoms.