Erythema nodosum following a jellyfish sting.

At least 100 of the approximately 9,000 species of coelenterates are dangerous to humans. The most common syndrome following an envenomation is an immediate intense dermatitis, with characteristic skin discoloration, local pain, and systemic symptoms. In this case report, we describe a case of erythema nodosum with articular manifestations following envenomation with an unknown jellyfish. Serological testing of the victim revealed marked elevation of immunoglobulins G and M directed against Physalia physalis, the Portuguese man-of-war. The patient's condition did not respond to conventional topical therapy for coelenterate envenomation, but was successfully managed with systemic corticosteroid therapy. This case demonstrates that the emergency physician should consider a delayed reaction to a marine envenomation in any victim who presents with an acute dermatological disease following immersion in marine coastal waters.