P08 A case of a 7-year-old female with SAPHO and CRMO treated successfully with IL-17A inhibitor after failure with Anti-TNFα biologic.

Abstract

7-year old female develops inflamed well demarcated annular patches with golden crust on the plantar surface of both feet. Treated initially for infected discoid eczema in the community. Unresponsive to topical corticosteroids and oral antibiotics. Patient then developed acute left sided lower limb (LLL) bone pain with no pyrexia and a c-reactive protein of 9. MRI imaging showed multiple sites of osteomyelitis in the LLL. Histology from bone aspirate was normal and gram stain/culture was negative. Case was reviewed by rheumatology/paediatric team at tertiary centre, and a diagnosis of SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) and CRMO (chronic recurrent multifocal osteomyelitis) was established. She commenced NSAIDs and Anti-TNFa biologic. 12 weeks into treatment the bone pain improved however, the patient developed paradoxical psoriasis on head, neck and limbs. Therapy was switched to IL-17A inhibitor with amelioration of paradoxical psoriasis and improvement seen in inflammatory patches on the plantar aspect of feet after 4 weeks. The prevalence of CRMO in the paediatric population is approximately 0.4/100 000 with a female preponderance. There are case reports in adult patients with SAPHO syndrome developing paradoxical psoriasis after adalimumab, with case series demonstrating improvement in palmoplantar pustulosis after secukinumab. More evidence is required to establish the efficacy of IL-17A inhibitors in the treatment of SAPHO in the paediatric age group. We present a patient with a rare case of SAPHO and CRMO with worsening cutaneous symptoms after commencing anti-TNFa. This paradoxical reaction cleared rapidly on switching to secukinumab (IL-17A inhibitor).