Erythema nodosum and erythema induratum (nodular vasculitis): diagnosis and management.

Erythema nodosum is the most common type of panniculitis; it may be due to a variety of underlying infectious or otherwise antigenic stimuli. The pathogenesis remains to be elucidated, but both neutrophilic inflammation and granulomatous inflammation are implicated. Beyond treating underlying triggers, therapeutic options consist mainly of nonsteroidal anti-inflammatory drugs, symptomatic care, potassium iodide, and colchicine. Erythema induratum (nodular vasculitis) is a related but distinctly different clinicopathologic reaction pattern of the subcutaneous fat. It is classically caused by an antigenic stimulus from Mycobacterium tuberculosis but may be associated with several other underlying disorders. After appropriate antimicrobial treatment in tuberculous cases, therapy for erythema induratum is similar to options for erythema nodosum.