What are the symptoms and treatment options for Erythema nodosum?

Erythema Nodosum: Symptoms and Treatment

Erythema nodosum presents with tender, erythematous subcutaneous nodules typically located bilaterally and symmetrically on the anterior tibial areas (shins), often accompanied by systemic symptoms including arthralgia and fatigue, and requires treatment of any underlying cause along with symptomatic management using NSAIDs as first-line therapy. 1

Clinical Presentation

Characteristic Skin Lesions

• Appearance: Raised, tender, erythematous subcutaneous nodules measuring 1-5 cm in diameter 1
• Distribution: Bilateral and symmetrical, predominantly on the anterior tibial areas (shins) 1
• Evolution: Initially bright red, then progressing to livid red or purplish, and finally exhibiting yellow or greenish appearance resembling a deep bruise 2
• Resolution: Does not ulcerate and typically heals without atrophy or scarring 2

Associated Symptoms

• Arthralgia (joint pain)
• Fatigue
• Fever
• Malaise 3

Demographic Patterns

• More common in women than men (3-5 times higher prevalence) 1, 3

Diagnostic Considerations

Common Misdiagnoses

• Cellulitis
• Infected insect bites
• Minor trauma 1

Warning Signs for Alternative Diagnoses

• Unilateral lesions
• Presence of fluid collection or fluctuance
• Ulceration
• History of trauma to the area
• Patient on anticoagulants or with bleeding disorders 1

Recommended Diagnostic Tests

1. Complete blood count with differential
2. Erythrocyte sedimentation rate and/or C-reactive protein
3. Testing for streptococcal infection (throat culture, rapid antigen test)
4. Chest radiograph
5. Skin biopsy in atypical cases 1, 4

Common Underlying Causes

• Infections: Streptococcal pharyngitis (most common identifiable cause), tuberculosis 4
• Inflammatory conditions: Sarcoidosis, inflammatory bowel disease (Crohn's disease, ulcerative colitis) 1
• Autoimmune disorders: Behçet's syndrome 1
• Medications: Oral contraceptives, certain antibiotics 4
• Other: Pregnancy, malignancies 2, 3
• Idiopathic: Many cases have no identifiable cause 5

Treatment Approach

First-Line Treatment

• NSAIDs for symptom management (2-12 weeks based on clinical resolution)
  • Options: Acetylsalicylic acid, ibuprofen, naproxen, indomethacin 1

Second-Line Treatment

• Colchicine: Particularly effective for recurrent cases and when associated with Behçet's disease or inflammatory bowel disease 1

Severe or Refractory Cases

• Systemic corticosteroids: Reserved for severe cases unresponsive to first-line therapy
  • Brief courses recommended to minimize side effects
  • Should be avoided if underlying infection hasn't been ruled out 1, 2

Persistent or Frequent Relapses

• Immunomodulators: Azathioprine, TNF-α antagonists (infliximab, adalimumab) may be considered 1

Supportive Care

• Rest and elevation of affected limbs
• Compression stockings to reduce edema
• Avoidance of prolonged standing or sitting
• Adequate pain management 1

Treatment Duration and Monitoring

• Treatment typically lasts 2-12 weeks, based on clinical resolution
• Relapse may occur after discontinuation, requiring reinstitution for another 4-8 weeks
• Regular follow-up necessary to:
  • Assess treatment response
  • Monitor for recurrence
  • Evaluate for signs of underlying disease progression 1

Special Considerations and Pitfalls

• NSAIDs contraindications: Peptic ulcer disease, renal impairment
• Corticosteroid risks: May mask underlying infections
• Oncological vigilance: Erythema nodosum can occasionally be a paraneoplastic symptom 3
• Misdiagnosis risk: Commonly confused with cellulitis in emergency settings 1

Prognosis

• Generally good prognosis, especially when underlying cause is identified and treated
• Typically self-limited condition, but may recur 1, 2