II. Epidemiology

  1. Incidence: 1-5 per 100,000
  2. Age: Peaks in 20-30 year range
  3. Gender
    1. Adults: Women predominate by a factor of 6 fold
    2. Children: Boys and girls are equally affected

III. Pathophysiology

  1. Prototype of septal Panniculitis
  2. Affects subcutaneous fat
  3. Cutaneous Type IV delayed hypersensitivity response

IV. Causes

  1. Idiopathic (up to 55% of cases)
  2. Infection
    1. Streptococcal Pharyngitis (up to 48% of EM cases)
    2. Mycoplasma
    3. Chlamydia
    4. Coccidioidomycosis
    5. Histoplasmosis
    6. Yersinia enterocolitis (in europe)
    7. MycobacteriaTuberculosis (see granulomatous disease)
  3. Granulomatous disease
    1. Tuberculosis
    2. Sarcoidosis (up to 25% of cases)
    3. Inflammatory Bowel Disease
  4. Drug Reaction (up to 10% of cases)
    1. Halides
    2. Sulfonamides
    3. Amoxicillin
    4. Gold
    5. Oral Contraceptives
  5. Pregnancy

V. Symptoms

  1. Prodrome: Acute phase response (1-3 weeks before rash)
    1. Fever
    2. Arthralgia
  2. Rash
    1. Painful "bumps" on legs

VI. Signs

  1. Characteristics
    1. Erythematous Nodules
    2. Nodules are deep, warm
    3. Nodules are exquisitely tender to touch
    4. Nodules 1-10 cm (typically 2 or more cm diameter)
  2. Course
    1. Initially firm
    2. Later become fluctuant
    3. Involute over 2 week period
    4. May appear Bruised during healing
    5. Heal completely within 2 months
      1. No ulcerations, atrophy or scarring
  3. Distribution
    1. Most common on bilateral lower legs
      1. Pretibial area, anterior shins
    2. Other area involved
      1. Extensor Forearm
      2. Thighs
      3. Trunk
  4. Lesions change color over time
    1. Evolve from red to purple to brown
    2. Typically fades without scarring in a few weeks

VII. Clinical variants

  1. Erythema Nodosum Migrans
    1. Persistent and minimally symptomatic lesions
  2. Subacute Nodular Migratory Panniculitis
    1. Coalescing Nodules form large Plaques on legs
  3. Chronic Erythema Nodosum

VIII. Labs

  1. Complete Blood Count (CBC) with Leukocytosis
  2. Sedimentation Rate (ESR) increased
  3. C-Reactive Protein increased
  4. Tuberculin Skin Test (PPD)
  5. Antistreptolysin-O titer
  6. Consider sending stool for Ova and Parasites
  7. Skin Biopsy (indicated in atypical cases)
    1. Inflammation confined to subcutaneous fat
    2. Acute lesions
      1. Septal widening
      2. Vessel wall inflammation
      3. NO Vasculitis
    3. Chronic lesions
      1. Giant cells
      2. Granulomas may be present

IX. Imaging

X. Differential Diagnosis

  1. Common
    1. Alpha-1 antitrypsin deficiency
    2. Lupus Panniculitis
    3. Lymphoma (cytophagic histiocytic Panniculitis)
  2. Less common
    1. Necrobiosis Lipoidica
    2. Scleroderma

XI. Management

  1. NSAIDs
  2. Bed rest with leg elevation
  3. Support stockings
  4. Potassium iodide 300-900 mg/day for one month
    1. Risk of Hyperthyroidism
  5. Consider Systemic Corticosteroids
    1. Contraindicated in Bacterial Infection or cancer
    2. Prednisone 60 mg daily and taper
  6. Intralesional injections of Corticosteroids

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Ontology: Erythema Nodosum (C0014743)

Definition (MSH) An erythematous eruption commonly associated with drug reactions or infection and characterized by inflammatory nodules that are usually tender, multiple, and bilateral. These nodules are located predominantly on the shins with less common occurrence on the thighs and forearms. They undergo characteristic color changes ending in temporary bruise-like areas. This condition usually subsides in 3-6 weeks without scarring or atrophy.
Definition (CSP) erythematous eruption commonly associated with drug reactions or infection and characterized by inflammatory nodules that are usually tender, multiple, and bilateral; these nodules are located predominantly on the shins with less common occurrence on the thighs and forearms; they undergo characteristic color changes ending in temporary bruise-like areas; this condition usually subsides in 3-6 weeks without scarring or atrophy.
Concepts Disease or Syndrome (T047)
MSH D004893
ICD9 695.2
ICD10 L52
SnomedCT 156363009, 200929004, 32861005
English Erythema Nodosum, ERYTHEMA NODOSUM, erythema nodosum (diagnosis), erythema nodosum, Erythema Nodosum [Disease/Finding], nodosum erythema, Erythema;nodosum, Nodosum - erythema, Erythema nodosum, EN - Erythema nodosum, Erythema nodosum (disorder), erythema; nodosum, nodosum; erythema, Erythema nodosum, NOS
French ERYTHEME NOUEUX, Erythème noueux, Érythème noueux
Portuguese ERITEMA NODOSO, Eritema nodoso, Eritema Nodoso
German ERYTHEMA NODOSUM, Erythema nodosum
Japanese 結節性紅斑, ケッセツセイコウハン
Swedish Knölros
Czech erythema nodosum, Erythema nodosum
Finnish Kyhmyruusu
Russian ERITEMA UZLOVATAIA, ERITEMA NODOZNAIA, ЭРИТЕМА НОДОЗНАЯ, ЭРИТЕМА УЗЛОВАТАЯ
Spanish ERITEMA NODOSO, eritema nodoso, eritema nudoso (trastorno), eritema nudoso, Eritema nudoso, Eritema Nudoso
Korean 결절홍반
Croatian ERITEM, NODOZNI
Polish Rumień guzowaty
Hungarian Erythema nodosum
Norwegian Knuterosen, Erythema nodosum
Dutch erytheem; nodosum, nodosum; erytheem, erythema nodosum, Erythema nodosum
Italian Eritema nodoso