Chronic lymphocytic leukemia presenting with symptomatic central nervous system involvement.

Leukemic infiltration of the central nervous system (CNS) resulting in neurological manifestations is a rare complication of chronic lymphocytic leukemia (CLL). Furthermore, symptomatic CNS involvement as the initial presentation of previously undiagnosed CLL is extremely rare. In the present report, the authors describe a case of an 89-year-old female previously diagnosed with Alzheimer's disease who suddenly developed rapidly worsening mental changes. Cytological and immunocytological examinations of the lymphoid cells present on the cerebrospinal fluid (CSF) revealed CNS involvement by a clonal B-cell lymphoproliferative disorder, most consistent with de novo B-CLL expressing kappa light chain restriction. Subsequently, flow cytometric analysis done on the peripheral blood lymphocytes confirmed the diagnosis of B-CLL in this patient. Thus, this study shows the potential usefulness of immunocytological evaluation in detecting monoclonal lymphoid populations on CSF samples in adult patients presenting with altered mental status and CSF pleocytosis of lymphocytes.