Borrelial lymphocytoma.

Borrelial lymphocytoma is a rare cutaneous manifestation of early localized European Lyme borreliosis. It manifests as a nodule or plaque with a diameter of up to a few centimeters. The lesion is, as a rule, solitary. It is more common in children than in adults and, in contrast to erythema migrans and acrodermatitis chronica atrophicans, has male predominance. A tick bite has been reported in approximately one half of patients; the tick bite is usually at the site or in the vicinity of the later borrelial lymphocytoma. The predilection site for the development of lesions is the breast in adults and the ear lobe in children. Borrelial lymphocytoma is frequently associated with erythema migrans, but rarely with other manifestations of Lyme borreliosis, and is predominantly caused by Borrelia afzelii. At presentation, approximately half of the patients with borrelial lymphocytoma have measurable serum borrelial antibodies and, in about one third, spirochetes can be cultivated from the skin lesion. A 14-day antibiotic therapy, as recommended for patients with erythema migrans, is highly successful. Posttreatment duration of a borrelial lymphocytoma is positively associated with the pretreatment duration of the lesion and with patient age, while treatment failure is associated with the clinical signs of disseminated Lyme borreliosis at presentation. Substantial improvements in knowledge on borrelial lymphocytoma and laboratory diagnostics in recent decades have contributed to earlier diagnosis and treatment. Consequently, borrelial lymphocytoma is usually a mild disease with a good prognosis.