Erythema Nodosum and Other Forms of Panniculitis

Panniculitis refers to a group of disorders characterized by inflammation of the subcutaneous fat. While panniculitis is relatively uncommon in childhood, it can be a challenge to diagnose. The majority of panniculitides present similarly as tender erythematous nodules or plaques on the lower extremities. The most commonly used classification system for panniculitides is based on the histopathological features, usually divided into predominantly septal inflammation versus predominantly lobular inflammation, and then further separated into processes with and without vasculitis. Panniculitis may be a primary disease, but is more often a secondary process that requires further evaluation for an underlying aetiology. Erythema nodosum is the most common form of panniculitis in both children and adults. This chapter discusses the panniculitides that have been reported to occur in childhood.