The objectives of the study were to characterize the clinical picture of paradoxical skin lesions in SAPHO patients treated with anti-TNF-α agents and to explore its pathogenesis. Patients treated with anti-TNF-α therapy were identified from a cohort of 164 SAPHO patients. The clinical data and skin biopsies were collected. The usage, efficacy, and side effects of anti-TNF-α therapy were recorded. Forty-one (25.0%) patients received anti-TNF-α therapy, of which seven (17.1%) developed paradoxical skin lesions after 1 to 14 infusions. Patients with such lesions were older at onset of skin lesions than those without (p = 0.034). Expression of TNF-α in palmoplantar pustulosis increased after anti-TNF-α therapy in the two examined patients with exacerbated skin lesions. Anti-TNF-α therapy induces paradoxical skin lesions in 17.1% SAPHO patients. Late onset of skin manifestations is associated with an increased risk of such lesions. The paradoxical elevation of TNF-α expression in lesions may contribute to this phenomenon.
Keywords: Age of onset; Palmoplantar pustulosis; Psoriasiform lesions; SAPHO syndrome; Side effects; Tumor necrosis factor-α inhibitor.