Cutaneous manifestations of B-cell chronic lymphocytic leukemia associated with Borrelia burgdorferi infection showing a marginal zone B-cell lymphoma-like infiltrate.

We report on a 69-year-old female patient with specific cutaneous manifestations of B-cell chronic lymphocytic leukemia that arose at the site of erythema chronicum migrans due to Borrelia burgdorferi infection. Histological examination revealed the presence of dense infiltrates of small hyperchromatic lymphocytes admixed with clusters of plasma cells. Immunohistology showed a CD5+/CD20+ phenotype of the lymphocytes and monoclonal expression of kappa immunoglobulin light chain by the plasma cells. Presence of Borrelia DNA was confirmed by polymerase chain reaction studies. The unusual histopathological and phenotypic findings described in this case of cutaneous manifestations of B-cell chronic lymphocytic leukemia associated with Borrelia burgdorferi infection may lead to the misdiagnosis of cutaneous marginal zone B-cell lymphoma.