B cell chronic lymphocytic leukemia with meningeal infiltration by T lymphocytes.

Chronic lymphocytic leukemia (CLL) is a generalized malignancy of the lymphoid tissue characterized by an accumulation of monoclonal lymphocytes, usually of the B cell type. Involvement of the central nervous system is a rare complication, usually seen in T cell leukemias. We report a case of a 78-year-old woman with B cell CLL and meningeal infiltration by both B and T lymphocytes, although predominantly T lymphocytes. Neurological symptoms were the first manifestation of this disease. Computed tomography of the brain was negative. The diagnosis of leukemic meningitis was made on the basis of the examination of the cerebrospinal fluid, and which included cytological and flow cytometry analysis. The patient was given systemic chemotherapy in the form of chlorambucil and intrathecal administration of methotrexate and dexamethasone. After recovery, she had regular follow-up. We assume that this rare case of CLL might have been biclonal, with both B and T cell types.