PSTPIP1 and pyoderma gangrenosum: The involved gene encodes the proline-serine-threonine phosphatase-interacting protein 1, a cytoskeleton-associated adaptor protein that binds pyrin and regulates IL-1 production; the syndrome is defined by self-limited episodes of oligoarthritides with an accumulation of neutrophil-rich, but sterile, material in the synovial fluid, severe pictures of pyoderma gangrenosum and disfiguring acne, which may evolve into necrotic plaques and atrophic scars [45].