Correspondence (letter to the editor): Additions

From a dermatological perspective, some points can be added to this very clearly structured article by Rauer et al. (1). In endemic areas, erythema migrans—the clinical marker of early Lyme disease—has such a high specificity that a laboratory diagnosis is generally not required, in contrast to Lyme neuroborreliosis. However, the histopathological evaluation of lesional skin is of diagnostic value as it helps to rule out important conditions in the differential diagnosis, such as unspecific arthropod reactions, erysipelas, granuloma annulare, or localized scleroderma. The biopsy is best obtained from the edge of the erythema. Histological findings include an inflammatory infiltrate with lymphocytes and histiocytes in the superficial dermis as well as dilated blood vessels as the pathologic correlate of the erythema, in the presence of normal epidermis.

Despite the mostly clinically self-limiting nature of erythema migrans, antimicrobial therapy is always required to prevent pathogen persistence and thus potential later Borrelia-induced diseases, such as Lyme neuroborreliosis, among others. Unlike some other courses of Lyme neuroborreliosis, erythema migrans can be successfully treated with oral antimicrobial therapy. The antibiotics used are doxycycline (2 × 100 mg or 1 × 200 mg daily orally for 10 –14 days) or amoxicillin, in pediatric patients aged less than 9 years amoxicillin or cefuroxime axetil, and during pregnancy and breastfeeding amoxicillin, each for 14 days (2). If (oral) antimicrobial therapy is planned, treatment adherence can be significantly improved if the patient is thoroughly informed about the importance of the treatment as well as potential side effects and drug interactions prior to start of treatment.

References