Successful combined antibiotic therapy with oral clindamycin and oral rifampicin for pyoderma gangrenosum in patient with PASH syndrome

Pyoderma gangrenosum (PG) is a neutrophilic dermatitis, the prevalence of which is unknown. The only reported incidence in the literature estimates that there are 3 to 10 cases per million annually in the United Kingdom.1 The association with digestive tract and inflammatory rheumatic disease, neoplasia, and endocrinopathies is well known.2 New autoinflammatory syndromes with PG have been described: PAPA syndrome, combining PG with pyogenic sterile arthritis and cystic acne; PASH syndrome, combining PG with cystic acne and hidradenitis suppurativa (HS); and PAPASH syndrome, combining PG with pyogenic sterile arthritis, acne, and HS.3 PAPA and PAPASH syndromes arise from mutations in the coding region of the proline-serine-threonine-phosphatase interacting protein 1 gene (PSTPIP1) resulting in the loss of inhibitory effect on the NALP3 inflammasome with production of interleukin (IL)-1β. For PASH syndrome, the only known anomaly is an increase in the number of CCTG repetitions in the PSTPIP1 promoter, with no known functional impact.4 First-line treatment for PG is generally based on systemic corticosteroid therapy or antibiotics with an anti-inflammatory action (eg, dapsone and tetracyclines) or immunosuppressive drugs (eg, azathioprine, cyclosporine, and mycophenolate mofetil). Also introduced recently are anti–tumor necrosis factor-α agents, anti–IL-1 (anakinra), and finally anti–IL-12–IL-23 (ustekinumab) and anti–IL-17 (ixekizumab). Studies investigating PASH syndrome found that cyclosporine and dapsone and biotherapy using anti–tumor necrosis factor-α5 and anti–IL-1 (anakinra)4 are effective. The clinical course is, however, marked by the risk of repeated relapses and resistance to conventional treatments for PG. Furthermore, any proposed therapeutic strategy should be effective against all 3 entities (ie, PG, HS, and cystic acne).