A novel de novo PSTPIP1 mutation in a boy with pyogenic arthritis, pyoderma gangrenosum, acne (PAPA) syndrome

Autoinflammatory disorders are a group of Mendelian disorders characterized by seemingly unprovoked inflammatory bouts without high-titer autoantibodies or antigen-specific T-cells and are probably due to defects in the innate immunity. We here report on a 4-year-old Arabic boy with the clinical presentation of an autoinflammatory disorder, namely Pyogenic Arthritis, Pyoderma Gangrenosum and Acne (PAPA) syndrome. The presentation includes abscess formation after immunization and recurrent mono-articular acute arthritis in various joints that responded favourably to systemic glucocorticosteroids, albeit without acne or pyoderma gangrenosum. The mutation analysis of the boy identified a novel de novo mutation in PSTPIP1, the gene responsible for PAPA syndrome. We recommend that the diagnosis of PAPA syndrome should be entertained in the differential diagnosis of patients with recurrent sterile pyogenic arthritis prior to the development of pyoderma gangrenosum or acne in order to initiate a timely management of the disorder.