FormalPara Patient 1

A 59-year-old male presented to clinic with 1 week of fatigue and chills after hiking in eastern Massachusetts 6 weeks prior to presentation. He recalled removing a tick from his left hip during the hike and subsequently noticed a new rash in that same location. Physical examination revealed a 5-cm circular, erythematous patch with violaceous center on his left hip (Fig. 1a).

Figure 1
figure 1

Two variants of erythema migrans. a Erythema migrans on the left hip in a 59-year-old male (patient 1) manifesting as a circular erythematous patch with violaceous center. b Bullous erythema migrans in the left popliteal fossa in a 56-year-old male (patient 2) manifesting as an oval erythematous plaque with diffuse coalescing vesicles and bullae and surrounding erythema.

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FormalPara Patient 2

A 56-year-old male presented to the emergency department with 3 days of malaise and rash. He had spent time at a barbecue in Massachusetts 5 days earlier, but did not recall any insect or tick bites. Physical examination revealed a 10-cm oval-shaped erythematous, non-tender plaque with vesiculobullous surface in the left popliteal fossa with surrounding erythema (Fig. 1b).

Both patients experienced complete resolution of symptoms and rash after receiving 21 days of doxycycline for treatment of presumed Lyme disease. While erythema migrans is present in up to 80% of patients with Lyme disease1, only 9% present with classic central clearing2. Given the poor sensitivity (<40%) of serological testing in patients with erythema migrans1 , 3 , 4, the diagnosis and prompt treatment of Lyme disease often depend on physicians’ ability to recognize its varied cutaneous manifestations.