Merging Patches, an Atypical Presentation of Disseminated Cutaneous Lyme Disease: A Case Report

Lyme disease, spread by the Ixodes tick, is typically associated with a single "bull's eye rash" that emergency physicians are comfortable recognizing and treating during the summer months when this disease is most prevalent. However, Lyme disease can also present in disseminated forms that are more difficult to diagnose.

We describe a phenomenon of disseminated Lyme with multiple rash complexes that is unrecognized by clinicians. A 65-year-old woman with no prior medical history presented with flu-like symptoms including headache, nausea, and arthralgias, as well as a nonpruritic rash on her lower limbs. On physical examination, multiple red, blanching patches with a diameter of up to 20 cm were seen. Although she was initially thought to have a nonsteroidal anti-inflammatory drug reaction as her skin biopsy for Borrelia burgdorferi was negative, an immunoglobulin M test for B. burgdorferi was found to be positive during her emergency department visit. Despite the diverging results, a diagnosis of early-disseminated Lyme was made. She was discharged home on a 3-week course of oral doxycycline, and a complete resolution of her symptoms was noted on a follow-up visit. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: With the incidence of Lyme disease and its atypical presentations on the rise, the emergency physician should be aware of the other rashes that are associated with this disease, particularly those associated with disseminated cutaneous Lyme. Early diagnosis of the disseminated forms of Lyme is critical to prevent the occurrence of life-threatening cardiovascular and neurological complications known to occur with this disease.