Diagnostic challenge of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome in pediatric age: A monocentric case series

SAPHO syndrome is a rare disease that typically begins in the third-fifth decade of life, and is characterized by osteoarticular and dermatologic features [1]. The acronym summarizes the key clinical features: synovitis, acne, palmoplantar pustulosis, hyperostosis and osteitis [2]. The prevalence of this condition is estimated to be less than 1 per 10,000 people [3]. Several cases have been described in childhood, mostly in adolescents, some associated with other comorbidities. Indeed, the SAPHO clinical spectrum encompasses a wide range of different manifestations which overlap with other autoimmune or autoinflammatory disorders, thus often challenging the diagnosis, particularly in paediatric age [4–6]. If promptly recognized and adequately treated, SAPHO syndrome shows a favourable course. Herein we present a case series of 5 children affected by SAPHO syndrome, diagnosed at our Rheumatology Unit from March 2015 to June 2020, experiencing an excellent response to anti-TNFα. Five Caucasian patients (3 males) with a median age of 12 years and 5 months (range 132-192 months) received a diagnosis of SAPHO syndrome (Table 1). The median time between disease onset and diagnosis was 6 months (range 3–22 months). Patient #1 and #2 had a previous diagnosis of Inflammatory Bowel Diseases (IBD) – Crohn disease (CD) and Ulcerative colitis (UC), respectively; no other previous or concomitant relevant medical conditions were reported for the other patients.