MedGen

Pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) is a rare autosomal dominant autoinflammatory disease that 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 predominate, including pathergy, frequently with abscesses at the sites of injections, severe cystic acne, and recurrent nonhealing sterile ulcers, often diagnosed as pyoderma gangrenosum (summary by Demidowich et al., 2012). [from OMIM]

An inflammatory arthritis characterized by purulent synovial fluid with neutrophil accumulation, but with negative cultures. [from HPO]