Diagnostic dilemma for the 1990s: Lyme disease versus rheumatic fever

A 15-year-old boy developed an annular erythematous skin rash, fever, knee pain, syncope, and was found to be in complete heart block requiring temporary transvenous pacing. His recovery was complete following therapy with high dose steroids, aspirin, and IV ceftriaxone followed by oral penicillin. Serologic tests documented diagnostic levels of antibodies to Borrelia burgdorferi as well as to Group A streptococcal DNase B. Diagnoses of both Lyme disease and rheumatic fever are based on clinical presentation and serologic confirmation. Our patient had a clinical presentation compatible with either diagnosis and serologic test results suggestive of infection by both B burgdorferi and Group A streptococci. The patient's management was aimed at preventing complications of both diseases, since clinicians involved with the patient's case could not agree on the most likely diagnosis. We present this case to emphasize the following: both rheumatic fever and Lyme disease should be considered in patients presenting with annular skin rashes and complete heart block; serologic studies may be confusing in both Lyme disease and rheumatic fever since neither is entirely sensitive nor specific and efforts should be made to document the causative organism by appropriate cultures, biopsies, and stains when possible; and improved immunoserologic testing for Lyme disease, in particular, is highly needed.