BACKGROUND: Lyme disease is the most common tick-borne illness in the USA, Canada, and Europe. Clinical manifestations vary greatly, with localized skin findings functioning as early signs of the disease, followed by disseminated disease. The rarest dermatologic presentation of Lyme is a borrelial lymphocytoma, occurring distinctly in Europe and caused typically by Borrelia afzelii. CASE PRESENTATION: We report a case of a Caucasian 5-year-old European-American boy with slowly progressing, painless edema and erythema of his right pinna. Travel history revealed significant exposure to ticks during a recent trip to Eastern Europe. Laboratory testing for Borrelia burgdorferi demonstrated mixed positivity. He was treated with a 21-day course of amoxicillin, with complete resolution of symptoms and no sign of secondary Lyme disease. CONCLUSIONS: Borrelial lymphocytoma is a rare manifestation of Lyme disease in North America, although not uncommon in Europe. Diagnosis is made by the presence of a painless erythematous swelling typically found on the ear lobe, nipples, or testes. Laboratory tests are available but with low sensitivity, therefore, a high index of suspicion is necessary for a clinical diagnosis to be made. Treatment for isolated borrelial lymphocytoma is doxycycline 4 mg/kg up to 100 mg twice daily, whereas for children less than 8 years of age amoxicillin 50 mg/kg divided three times daily, for 3-4 weeks, is preferred.