Atypical erythema Migrans with generalized maculopapular rash in a child: A case report of Lyme disease and review of the literature

Abstract

Lyme disease (LD) is a multisystem zoonosis caused by Borrelia species and is transmitted by ticks. Erythema Migrans (EM) is the most common early manifestation and a key diagnostic sign, but atypical morphologies are frequent and may be underrecognized. Generalized rash concurrent with EM is rare in paediatric LD. We report a 6-year-old girl presenting with acute right lower limb pain, low-grade fever, and a generalized blanchable maculopapular rash. Physical examination revealed an atypical EM lesion on the right thigh, characterized by an almost homogeneous erythematous patch with diamond-shaped borders, lacking the classic “bull’s eye” configuration. Laboratory findings showed elevated inflammatory markers, normal blood count, and negative microbiological tests for alternative aetiologies. Serology was positive for Borrelia burgdorferi IgM and confirmed by Western blot. The patient was treated with oral doxycycline, achieving rapid symptom resolution. At 15-month follow-up, she reported occasional limb arthralgia without neurological symptoms or need for medication. This case adds to the scarce literature describing generalized rash in association with EM in children. The coexistence of these cutaneous features may indicate early disseminated LD and warrants clinical suspicion, even in the absence of a known tick bite. Recognition of atypical EM morphologies is crucial for timely diagnosis and treatment, particularly in endemic areas. Long-term follow-up is advised due to the risk of post-treatment Lyme disease syndrome (PTLDS), which can present with persistent musculoskeletal or neurocognitive symptoms.