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erythema chronicum migricans (erythema migrans)

Etiology: - associated with early, localized Lyme disease (Borrelia burgdorferi) - recurrent erythema migrans represents reinfection with a different genotype of Borrelia burgdorferi rather than relapse [3] - Southern tick-associated rash illness Epidemiology: - 80% of patients with Lyme disease Clinical manifestations: 1) lesion develops subsequent to & surrounding the site of a tick bite 2) incubation period 5-14 days 3) annular, sometimes urticarial, erythematous lesion with central clearing [2] - 'bullseye' appearance 4) lesions are single (75%) or multiple (25%) 5) lesions > 5 cm in size 6) lesions expand over days, resolve over weeks 7) systemic symptoms common & may be only manifestation * images [5,6,7,8,9,10,11] Laboratory: - no laboratory testing recommended [2] - arguments for no testing in [2] less than convincing - Borrelia burgdorferi DNA from skin biopsy - Borrelia burgdorferi serology may be negative in early, localized Lyme disease Differential diagnosis: - tick bite reaction: a) incubation period hours b) size: < 1 cm c) expands over hours, resolves over days d) systemic symptoms rare - Streptococcal cellulitis a) progresses over hours b) very tender c) patients often very ill - burn (history) - fixed drug eruption (history) - dermatophyte infection a) less erythema b) evolves more slowly than erythema migrans c) raised active border with central clearing - necrotic spider bite (endemic areas) - nummular eczema Management: - see Lyme disease - empiric oral therapy 14-21 days, regardless of cause [2] (however, it would seem prudent to determine the cause) - 1st line agents - doxycycline 100 mg PO BID - amoxicillin 500 mg PO TID - cefuroxime 500 mg PO BID - alternative agent: azithromycin 500 mg PO QD - intravenous ceftriaxone for cardiac or neurologic manifestations or evidence of disseminated Lyme disease

Related

Lyme disease

General

sign/symptom skin lesion

References

  1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 176
  2. Medical Knowledge Self Assessment Program (MKSAP) 15, 16, 17, 18. American College of Physicians, Philadelphia 2009, 2012, 2015, 2018. - Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025
  3. Physician's First Watch, Nov 15, 2012 David G. Fairchild, MD, MPH, Editor-in-Chief Massachusetts Medical Society http://www.jwatch.org - Nadelman RB et al. Differentiation of reinfection from relapse in recurrent Lyme disease. N Engl J Med 2012 Nov 15; 367:1883 - Steere AC. Reinfection versus relapse in Lyme disease. N Engl J Med 2012 Nov 15; 367:1950
  4. Stonehouse A, Studdiford JS, Henry CA An update on the diagnosis and treatment of early Lyme disease: "focusing on the bull's eye, you may miss the mark". J Emerg Med. 2010 Nov;39(5):e147-51. Epub 2007 Oct 18. PMID: 17945460
  5. Wikipedia: Erythema chronicum migrans (image) https://en.wikipedia.org/wiki/Erythema_chronicum_migrans
  6. MedicineNet.com Picture of Lyme Disease (Erythema-Migrans) http://www.medicinenet.com/image-collection/lyme_disease_erythema-migrans_picture/picture.htm
  7. Centers for Disease Control and Prevention (CDC) Signs and Symptoms of Untreated Lyme Disease. http://www.cdc.gov/lyme/signs_symptoms/
  8. Blanton L, Keith B, Brzezinski W. Southern Tick-Associated Rash Illness: Erythema Migrans Is Not Always Lyme Disease Medscape http://www.medscape.com/viewarticle/583023 South Med J. 2008;101(7):759-760. PMID: 18580719
  9. DermNet NZ. Lyme disease http://www.dermnetnz.org/bacterial/lyme.html
  10. Burns DO 7 Bug Bites You Need to Know Medscape. June 17, 2021 https://reference.medscape.com/slideshow/bug-bites-6004328
  11. Steele RW Lyme disease Medscape. June 15, 2022 https://reference.medscape.com/slideshow/tick-borne-illnesses-6006369