II. Definition

  1. Pathognomonic bullseye rash of early Lyme Disease

III. Epidemiology

  1. Now thought to occur in 90% of Lyme Disease cases
    1. Previously thought to be seen in only 50-60%
    2. Lower detection due to ECM rash that is missed
    3. Reinforces need for very careful skin exam
  2. Appears in 86-100% of symptomatic Lyme Disease cases

IV. Timing

  1. Occurs 3-30 days (median 7 days) after deer Tick Bite

V. Distribution

  1. Localized rash at deer Tick Bite site

VI. Appearance

  1. Initial
    1. Small red painless Papule at Tick Bite site
    2. Rash does not itch
    3. Expands centrifugally over days or weeks
  2. Later: Annular Lesion
    1. Circular, oval or triangular
    2. Central clearing or darkening with induration (bullseye or target appearance)
      1. Occurs in only 19-33% of cases
    3. Macular, papular or vesicular
    4. Rapid and prolonged expansion (unique to Erythema Migrans)
    5. Expands to >5 cm diameter
      1. Typically 20-30 cm (up to 70 cm) diameter
      2. Contrast with Insect Bite reaction
  3. Resolution
    1. Rash resolves in weeks if not treated
  4. Variations
    1. Multiple lesions (hematogenous spread of infection) in 10-20% of cases
    2. Central vessicle or Pustules (5% of cases)
    3. May appear purpuric on legs

VII. Symptoms

VIII. Differential Diagnosis

  1. See Annular Lesion
  2. Localized hypersensivity reaction to Insect Bite
    1. Typically <2.5 to 5 cm in size
    2. Course
      1. Onset while tick still attached
      2. Starts to resolve within 48 hours
    3. Distinguish from Erythema Migrans
      1. Mark margins
      2. Observe for 48 hours off antibiotics
      3. Improvement suggests not a Lyme Disease rash
  3. Contact Dermatitis
    1. Pruritus (does not occur in Erythema Migrans)
  4. Cellulitis
    1. Distribution may help distinguish from EM rash
    2. Cellulitis uncommon in typical eyrthema migrans sites: Axilla, popliteal fossa, Abdomen, back and groin
  5. Erythema Multiforme
    1. Multiple target lesions each typically <2 cm diameter
  6. Granuloma Annulare
    1. Scaling erythematous lesions with central clearing (esp. hands and feet)
  7. Methicillin Resistant Staphylococcus Aureus (MRSA)
    1. Lesions with necrotic central eschar
  8. Tinea Corporis
  9. Urticaria

IX. Interpretation: Classic Erythema Migrans rash

  1. Erythema Migrans is diagnostic for Lyme Disease
    1. Allows diagnosis without confirmatory testing
    2. Erythema Migrans is the only CDC-supported non-laboratory finding for definitive Lyme Disease diagnosis

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Ontology: Erythema Chronicum Migrans (C0014740)

Definition (MSH) A deep type of gyrate erythema that follows a bite by an ixodid tick; it is a stage-1 manifestation of LYME DISEASE. The site of the bite is characterized by a red papule that expands peripherally as a nonscaling, palpable band that clears centrally. This condition is often associated with systemic symptoms such as chills, fever, headache, malaise, nausea, vomiting, fatigue, backache, and stiff neck.
Concepts Disease or Syndrome (T047)
MSH D015787
SnomedCT 69588003, 186979009
English Erythema chronicum migrans, ECM - Erythema chronic migrans, erythema chronicum migrans, erythema chronicum migrans (physical finding), annular lesion with erythema chronicum migrans, erythema migrans due to lyme disease (diagnosis), erythema migrans due to Lyme disease, Erythema Chronicum Migrans [Disease/Finding], erythema migrans chronicum, Erythema migrans, Erythema Chronicum Migrans, Erythema chronicum migrans (disorder), Erythema chronica migrans, ECM - Erythema chronicum migrans, Erythema chronica migrans (disorder), chronicum migrans; erythema, erythema; chronicum migrans, Borrelia; infection, burgdorferi (erythema chronicum migrans), infection; Borrelia, burgdorferi (erythema chronicum migrans)
Dutch erythema chronicum migrans, Borrelia; infectie, burgdorferi (Erythema chronicum migrans), chronicum migrans; erytheem, erytheem; chronicum migrans, infectie; Borrelia, burgdorferi (Erythema chronicum migrans), Erythema chronicum migrans
French Erythème chronique migrateur, Érythème chronique migrateur, Erythema chronicum migrans
Portuguese Eritema crónico migrante, Eritema Migrans Crônico
Spanish Eritema migratorio crónico, eritema migratorio crónico (trastorno), eritema migratorio crónico, Eritema Crónico Migrans
Japanese 慢性遊走性環状紅斑, マンセイユウソウセイカンジョウコウハン
Swedish Erythema chronicum migrans
Czech erythema migrans, erythema chronicum migrans, Erythema chronicum migrans
Finnish Vaeltava punoitus
Polish Rumień przewlekły wędrujący
Hungarian Erythema chronicum migrans
Norwegian Erytem, kronisk migrerende, Erythema chronicum migrans, Kronisk migrerende erytem
German Erythema chronicum migrans
Italian Eritema cronico migrante