Lyme borreliosis mimicking central nervous system malignancy: the diagnostic pitfall of cerebrospinal fluid cytology

We report two children with acute loss of neurological functions and signs of an increased intracranial pressure. Imaging techniques ruled out space o ccupying lesions, whereas CSF cytology indicated CNS involvement of a non-H odgkin lymphoma in the form of abnormal lymphocytic pleocytosis with malign ancy criteria fulfilling lymphoid cells. CSF protein electrophoresis and Bo rrelia burgdorferi serology revealed neuroborreliosis which was successfull y treated with antibiotic therapy. The malignancy mimicking cytology is bas ed on a blastoid transformation of B- and T-lymphocytes due to the antigeni c stimulus of B. burgdorferi infection. Lymphoid cells in the CSF of a pati ent with acute or chronic neurological symptoms raise the differential diag nosis of inflammatory etiology versus CNS lymphoma. Monomorphism and higher quantity of the lymphoid cells point to CNS lymphoma. A lower quantity and polyclonal pattern of lymphoid cells associated with an elevated protein f raction caused by intrathecal immunoglobulin synthesis: suggest an inflamma tory etiology. (C) 2000 Elsevier Science B.V. All rights reserved.