Erythema nodosum.

Erythema nodosum is the most common and, in its classic form, the most easily recognized cause of inflammatory nodules on the legs. It is characterized by inflammatory, tender, nonulcerating, nonscarring nodules that are typically multiple and bilateral. The rather characteristic clinical presentation can be attributable to one of many causes or associated with a wide spectrum of systemic diseases. Diagnosis, evaluation, and treatment are discussed.