PSTPIP1 and Arthritis: In a more restricted subset of patients, PG represents a component of distinct autoinflammatory syndromes [18], whose prototype is PAPA (pyogenic arthritis, PG and acne), hallmarked by sterile cutaneous inflammation and arthritis and caused by pathogenic variants in PSTPIP1 (proline-serine-threonine phosphatase interacting protein 1) gene that lead to an altered proinflammatory signaling and neutrophil-driven inflammation [18].