Pyoderma gangrenosum is a rare, inflammatory skin disease where painful pustules or nodules become ulcers that progressively grow.

[10][11] Marzano et al. (2017) identified a variety of single-nucleotide polymorphisms (SNPs) linked to autoinflammation that were carried, singly or in combination, in subsets of patients with pyoderma gangrenosum, acne and suppurative hidradenitis syndrome (PASH syndrome) or isolated pyoderma gangrenosum of the ulcerative subtype.

[15] Diagnosis of PG is challenging owing to its variable presentation, clinical overlap with other conditions, association with several systemic diseases, and absence of defining histopathologic or laboratory findings.

[citation needed] First-line therapy for disseminated or localized instances of pyoderma gangrenosum is systemic treatment with corticosteroids and ciclosporin.

Pyoderma gangrenosum ulcers demonstrate pathergy, that is, a worsening in response to minor trauma or surgical debridement.

[citation needed] Papules that begin as small "spouts" can be treated with Dakin's solution to prevent infection and wound clusters also benefit from this disinfectant.