Clin Dermatol. 2006 Nov-Dec;24(6):509-20.
Diagnosis, treatment, and prognosis of erythema migrans and Lyme
arthritis.

M Feder H Jr, Abeles M,Bernstein M,Whitaker-Worth D,Grant-Kels JM.
Division of Infectious Diseases, University of Connecticut Health
Center, Farmington, CT 06030, USA; Department of Pediatrics,
Connecticut Children's Medical Center.



Most patients with erythema migrans, the pathognomonic rash of Lyme
disease, do not recall a deer tick bite. The rash is classically 5 to
68 cm of annular homogenous erythema (59%), central erythema (30%),
central clearing (9%), or central purpura (2%). Serologic testing is
not indicated for patients with erythema migrans, because initially,
the result is usually negative. Successful treatment of a patient with
erythema migrans can be accomplished with 20 days of oral doxycycline,
amoxicillin, or cefuroxime axetil. Patients with Lyme arthritis usually
present with a mildly painful swollen knee. Patients with Lyme
arthritis have markedly positive serology and can usually be
successfully treated with 28 days of oral doxycycline or amoxicillin.
Some patients may have persistent effusion despite 4 to 8 weeks of
antibiotics and may need synovectomy. Persistent effusion is not due to
persistent infection. Antibiotic therapy for more than 8 weeks for
patients with Lyme disease is not indicated. Chronic Lyme disease due
to antibiotic resistant infection has not been demonstrated.


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