PASH syndrome is an exceedingly rare disorder characterized by the triad of pyoderma gangrenosum (PG), acne, and hidradenitis suppurativa (HS).

The clinical course of PASH syndrome varies, but most individuals typically present with recurrent and episodic severe, nodulocystic, scarring acne and HS lesions during adolescence. PG lesions typically occur later in adulthood.

The genetics and pathophysiology of PASH syndrome remain largely unknown. However, proinflammatory cytokines interleukin (IL)-1 and tumor necrosis factor (TNF) are elevated in skin biopsies. Unlike PAPA syndrome, these cytokines are typically absent from peripheral blood, suggesting that systemic inflammation in PASH syndrome may be less pronounced. Additionally, mutations in several genes, including PSTPIP1 and NCSTN, have been identified in a small number of individuals with PASH syndrome.