Vesicular erythema migrans: an atypical and easily misdiagnosed form of Lyme disease.

Erythema migrans is the initial sign in the majority of patients infected with Borrelia, the genus of spirochetes that causes Lyme disease. Early identification and treatment decrease the risk of progression to later stages of disease. Although a "bull's eye" appearance owing to lesional clearing is considered classic for erythema migrans, this feature is surprisingly often lacking among patients in the United States. Furthermore, cutaneous Lyme disease can exhibit a wide range of morphologic variability in a minority of patients. Herein, we describe the case of a patient with Lyme disease in which the presence of atypical vesicular features, in conjunction with the initial absence of clearing, resulted in multiple misdiagnoses and delayed treatment. We also review the literature on the epidemiology and management of erythema migrans for cases in which the diagnosis may pose a challenge.