PAPASH syndrome is a rare genetic autoinflammatory condition consisting of the following tetrad: pyogenic arthritis, pyoderma gangrenosum (PG), acne vulgaris, and hidradenitis suppurativa (HS). It is thought to be due to a mutation in the PSTPIP1 gene that affects the innate immune system.

PAPASH should be distinguished from the following PG syndromes: PAPA (pyogenic arthritis, PG, and acne), PASH (PG, acne, and HS), and PsAPASH (psoriatic arthritis, PG, acne, and HS). These rare inflammatory syndromes are thought to share a common mechanism of interleukin (IL)‐1‐driven episodes of neutrophil‐predominated sterile inflammation.