Pyogenic Arthritis, Pyoderma Gangrenosum Acne (PAPA) Syndrome
The metabolic lesion causing the PAPA syndrome is alteration of the protein PSTPIP-1 (proline, serine, threonine, phosphatase interactive protein). PSTPIP-1 co-localizes with pyrin in neutrophils. Mutations in its encoding gene produces a hyperphosphorylated product.
The hyperphosphorylated PSTPIP-1 binds more avidly to pyrin, and in so doing, reduces pyrin’s braking on inflammasome activation.
Inherited as an autosomal dominant, the PAPA syndrome is characterized by sterile pyogenic arthritis, pyoderma gangrenosum and acne. The onset of acne coincides with puberty. Sterile skin abscesses may also be encountered