How is Erythema Nodosum (EN) managed?

Management of Erythema Nodosum

Treatment of erythema nodosum should primarily target the underlying condition if identified, with systemic corticosteroids indicated for severe cases and immunomodulatory agents reserved for resistant or recurrent cases. 1, 2

Diagnosis and Clinical Features

• Erythema nodosum (EN) presents as raised, tender, red or violet subcutaneous nodules of 1-5 cm in diameter, typically on the extensor surfaces of extremities, particularly the anterior tibial areas 1, 2
• Diagnosis is primarily clinical based on characteristic appearance; biopsy is not usually necessary except in atypical cases 1, 2
• EN commonly occurs during times of inflammatory bowel disease activity when associated with IBD 1
• The condition is idiopathic in approximately 32% of cases, with post-streptococcal infection (32%), sarcoidosis (11%), and tuberculosis (7%) being common identifiable causes 3

Treatment Algorithm

First-Line Management:

• Identify and treat the underlying condition (e.g., streptococcal infection, inflammatory bowel disease, sarcoidosis) 2, 4
• Bed rest and leg elevation to reduce discomfort 5, 6
• NSAIDs for pain management and to enhance resolution 5, 6

For Moderate to Severe Cases:

• Systemic corticosteroids are indicated, especially when associated with inflammatory bowel disease flares 1, 2
• For EN associated with Behçet's disease, colchicine should be preferred as first-line therapy 1

For Resistant or Recurrent Cases:

• Immunomodulation with azathioprine for frequent relapses, particularly in IBD-associated EN 1, 2
• Biologic agents (TNF-alpha inhibitors like infliximab or adalimumab) for cases resistant to conventional therapy, especially in IBD-associated EN 1, 2
• Interferon-alpha (IFNα) may be considered in resistant cases, particularly in Behçet's disease 1

Special Considerations

• EN associated with IBD typically requires treatment of the underlying bowel inflammation 1
• For EN associated with Behçet's disease, topical measures should be first-line for isolated lesions, with colchicine as the systemic treatment of choice 1
• Leg ulcers in patients with EN may have different causes (post-thrombotic vs. vasculitic) and treatment should be planned accordingly 1
• EN does not ulcerate and heals without atrophy or scarring; any ulceration suggests an alternative diagnosis 5

Monitoring and Follow-up

• Monitor for disease activity in associated conditions like inflammatory bowel disease or sarcoidosis 2
• Recurrent EN may indicate persistent underlying disease activity and warrants reassessment 2, 7
• Response to treatment is typically good, with most cases resolving within a few weeks 5, 6

Common Pitfalls to Avoid

• Failing to search for underlying causes before diagnosing idiopathic EN 7, 3
• Using immunosuppressive agents without ruling out infectious causes 5, 4
• Neglecting to monitor for disease activity in associated conditions 2
• Misdiagnosing ulcerating lesions as EN (true EN never ulcerates) 5