LAUSR

Objective Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome encompasses heterogeneous dermatological manifestations, mainly palmoplantar pustulosis (PPP) and severe acne (SA). This study aims to explore the necessity of stratified management according to skin lesions. Methods In a cohort of SAPHO patients, we compared the demographic, clinical, and scintigraphic characteristics of the SAPHO patients whose skin lesion was PPP or SA. Results A total of 249 patients were included (227 affected by PPP and 22 affected by SA). Patients with SA were younger at onset (20, interquartile ranges (IQR) 15–30 vs. 37, IQR 30–46 years old; p  < 0.001) and enrollment (35, IQR 25–38 vs. 41, IQR 33–50 years old; p  = 0.001), and they had a prolonged disease duration (88.5 months, IQR 18.7–216.0 vs. 16.0, IQR 7.0–48.0 months; p  < 0.001) and time needed for diagnosis (7.5, IQR 2.0–19.0 vs. 1.0, IQR 1.0–4.0 years; p  < 0.001). Adjusted by age, sex, and disease duration, SA was significantly associated with more disease-modifying anti-rheumatic drug (DMARD) use (adjusted odds ratio (OR) 3.72; 95% confidence interval (CI) 1.23, 12.62; p  = 0.019) and more sternoclavicular joint involvement (adjusted OR 5.91; 95% CI 1.17, 61.3; p  = 0.030) in two separate Firth's logistic regression models. Conclusion SAPHO patients affected by PPP or SA as the only skin lesion may have different epidemiologic features, osteoarticular manifestations, and treatment history. Key Points • SAPHO patients with PPP or SA were heterogenous in both demographic, clinical, and imaging features. • SAPHO patients with SA were mainly male and had a significantly younger age and longer duration of symptoms before diagnosis. • SA in SAPHO patients was significantly associated with more sternoclavicular involvement and more DMARD use history.