Systemic Juvenile Idiopathic Arthritis/Pediatric Still’s Disease, a Syndrome but Several Clinical Forms: Recent Therapeutic Approaches

Background: Systemic Juvenile Idiopathic Arthritis (SJIA)/Pediatric Still’s disease is associated with different phenotypes and outcomes from currently available treatments. Methods: A review of opinion, based on personal experience in a reference pediatric rheumatology center and key publications, to explore the most important questions regarding disease heterogeneity and treatment approaches. Results: A few situations deserve particular attention: 1/patients with recent-onset SJIA who may benefit from a treat-to-target approach with a key place for interleukin (IL)-1 inhibition; 2/SJIA patients refractory to Il-1 and IL-6 antagonists in whom several options may be discussed, including thalidomide or allogeneic hematopoietic stem cell transplantation; 3/SJIA patients with macrophage activation syndrome who may benefit from both well-used classical treatment and innovative approaches, such as anti-interferon gamma therapy or Janus Kinase (JAK) inhibitors; 4/SJIA with severe lung involvement, 5/SJIA patients who achieve complete remission on treatment, with some recent evidence that treatment may be reduced in intensity but not so easily withdrawn. Conclusions: a case-by-case discussion with expert teams is recommended in this heterogeneous, often difficult-to-treat population of patients.