Early Seronegative Lyme Disease Presenting With Erythema Migrans: Clinical Recognition and Management of a Case

Lyme borreliosis is the most prevalent tick-borne malady in the Northern Hemisphere, with erythema migrans (EM) serving as the signature of early localized disease. We describe the case of a middle-aged woman who exhibited a typical expanding EM lesion after a confirmed tick bite. Laboratory investigations, including complete blood count and inflammatory markers, were within normal limits, and Borrelia burgdorferi IgM and IgG serology were negative. Despite the absence of serological confirmation, the typical clinical presentation supported a diagnosis of seronegative early Lyme borreliosis. Empirical doxycycline therapy was initiated promptly based on clinical findings. The patient showed complete resolution of the skin lesion within 15 days and did not develop any systemic manifestations during follow-up. This case underscores the limited sensitivity of serological testing in early Lyme disease and highlights the importance of recognizing EM as a clinical diagnosis requiring immediate treatment without delay for laboratory confirmation.