Background. Information on the course and outcome of borrelial lymphocytoma (BL) is limited.
Methods. The study comprised 144 adult patients (75 female, 69 male; median age, 49 years) who had BL diagnosed at a single center between 1986 and 2014 and were followed up for 1 year.
Results. BL was located on the breast in 106 patients (73.6%), on the ear lobe in 27 (18.8%), and elsewhere in 11 (7.6%). The median duration of BL before diagnosis was 27 days (interquartile range [IQR], 9–68 days). Concomitant erythema migrans was registered in 104 of 144 patients (72.2%); other objective manifestations of Lyme borreliosis (LB) were present in 11 (7.6%). Immunoglobulin M and/or G borrelial serum antibodies were present in 72 patients (50%). Borreliae were isolated from BL lesions in 14 of 42 patients (33.3%) who had not received antibiotics before skin biopsy. Of 13 typed Borrelia strains, 11 were B. afzelii, 1 was B. garinii, and 1 was B. bissettii. The median duration of BL after starting antibiotic treatment was 21 days ([IQR], 10–30 days); the average duration was longer in patients who were older, had longer BL duration before treatment, or had signs of disseminated LB. Treatment failure occurred in 14 of 144 patients (9.7%). Patients with signs or symptoms of disseminated LB before treatment had nearly 4 times higher odds of treatment failure (95% confidence interval, 1.22–13.07) than those without such symptoms. All patients with treatment failure had uneventful outcome after retreatment.
Conclusions. BL is a rare manifestation of early localized LB. Fourteen-day antibiotic treatment, as used for erythema migrans, is effective.