Acute Erythema Nodosum

**Semantic type:** Finding

**Definition:** A septal panniculitis characterized by the sudden onset of painful, firm, erythematous nodules or plaques that most commonly erupt on the pretibial extensor surfaces. Though generally idiopathic and self-limited, this disorder may be a sign of a co-morbid systemic disease or the sequela of the use of certain medications.

**Synonyms:** - Erythema nodosum, acute form