Management of pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is an uncommon ulcerative skin disease often associated with underlying systemic diseases. Its pathogenesis is unknown, although immune pathways have been implicated. Targeted therapy is therefore lacking and currently treatment is largely empirical and consists of corticosteroids and ciclosporin first line. This paper reviews the current and emerging knowledge about PG. PG occurs with an incidence of 3-10 per million per year. The ulcers are exquisitely painful and characteristically have a necrotic centre with irregular overhanging bluish borders. Around half of cases are associated with underlying systemic disease, most commonly inflammatory bowel disease, rheumatoid arthritis and haematological malignancies; the remaining cases are idiopathic. The pathogenesis is unknown, but the most widely supported theory is immunological, and biopsies of lesions show a predominantly neutrophilic infiltrate. Several aberrant immune processes have been described, with neutrophils and their recruitment to sites of inflammation by cytokines taking an apparently important role. Topical and systemic therapies are both vital aspects of treatment, and in recent years, immune modulators have been used with increasing success, with an emerging role for anti-tumour necrosis factor alpha agents such as the monoclonal antibody infliximab. Although uncommon, PG causes significant morbidity to those it affects. Further research is needed into the disease pathogenesis, and adequate targeted treatment. © The Royal Society of Medicine.