Nicolau syndrome following etanercept administration

Nicolau syndrome (NS), or embolia cutis medicamentosa, is a well-known but rare adverse effect of a still largely unidentified pathogenesis, observed primarily after the intramuscular administration of various drugs. NS is characterized by immediate excruciating pain, early pallor and erythema and oedema at the injection site, followed by cutaneous, subcutaneous and even muscular aseptic necrosis in a livedoid pattern. It is a potentially serious reaction that is little influenced by which drug is injected. A case is reported of NS following a subcutaneous self-injection of etanercept for psoriasis and psoriatic arthritis. This case is remarkable because NS developed after subcutaneous and not after intramuscular drug administration, and because no cases of NS following the injection of tumour necrosis factor alpha inhibitors have been reported in the literature or in the World Health Organization adverse drug reactions database. Although not directly linked to the drug, the occurrence of NS has to be considered in patients receiving biological agents.