Erythema Nodosum

Background

• Erythema nodosum is present as tender, warm, erythematous subcutaneous nodules, usually located symmetrically on pretibial surfaces.
• Many causes appear to trigger erythema nodosum, including streptococcal infection, chronic inflammatory or autoimmune diseases, and medications, but 30%-50% of cases are idiopathic.

Evaluation

• Most patients can be diagnosed clinically by a thorough history and examination. Consider skin biopsy into the subcutaneous fat and tissue culture if infection is suspected or atypical lesions.
• Further evaluation for underlying causes may include testing for streptococcal infection, complete blood count, and testing as needed for sarcoidosis, tuberculosis, other infectious, or other causes as guided by clinical findings.

Management

• Treat any underlying identifiable cause according to usual care.
• Most lesions resolve spontaneously and management is mostly supportive with rest and nonsteroidal anti-inflammatory drugs (NSAIDs) for pain if needed.
• Oral corticosteroids may be used for rapid resolution of lesions if required, but infection, particularly tuberculosis, should be excluded first.