Mini erythema migrans - A sign of early Lyme borreliosis

Background: An erythema migrans (EM) remaining smaller than 5 cm in
diameter, called mini EM by us, has not been addressed in detail.
Objective: To study the significance of the mini EM as a sign of
Lyme borreliosis. Methods: Patients with suspected mini EM were
retrospectively selected out of 257 consecutive patients with EM.
The diagnosis of mini EM rested on the cultivation of Borrelia
burgdorferi. Species and subtype analysis of culture isolates was
performed using outer surface protein A (OspA) polymerase chain
reaction followed by restriction fragment length polymorphism and
sequencing of the OspA gene. Results: There was one patient with
definite (0.4%) and another patient with a questionable mini EM.
Borrelia garinii OspA type 6 was identified in the patient with the
definite and B. burgdorferi sensu lato in the patient with the
questionable mini EM. Conclusion: The mini EM represents an
important and apparently uncommon sign of early Lyme borreliosis.