Interleukin-1 receptor antagonist treatment revealed active hepatitis B infection in a boy with PAPA syndrome.

Background PAPA syndrome (pyogenic sterile arthritis, pyoderma gangrenosum and acne) is a rare autosomal-dominant autoinflammatory disease caused by mutations in PSTPIP1gene. Typically presents with recurrent sterile, erosive arthritis in childhood, occurring spontaneously or after minor trauma, occasionally resulting in significant joint destruction. By puberty, joint symptoms tend to subside and cutaneous symptoms increase. Cutaneous manifestations include pathergy, frequently with abscesses at the sites of injections, severe cystic acne, and recurrent nonhealing sterile ulcers, often diagnosed as PG.