Involvement of central nervous system in prolymphocytoid transformation of chronic lymphocytic leukemia.

We report a rare case of involvement of the central nervous system (CNS) by chronic lymphocytic leukemia (CLL). A 68-year-old man with prolymphocytic variant of B-CLL (CLL/PLL), develops CNS involvement with headache and vomiting. Computed tomography of the head showed no abnormalities. The cerebrospinal fluid (CSF) revealed numerous lymphocytoid cells of prolymphocytic appearance consistent with findings on the peripheral blood smear. Immunophenotypic analysis demonstrated that the leukemic B cells were positive for CD19, CD20, and HLA-DR, but CD5 was difficult to detect. The patient was treated with intrathecal methotrexate, cytarabine, and hydrocortisone and had improvement in symptoms and CSF findings. Although CNS involvement is an unusual manifestation in CLL, one should be aware of the possibility of this complication in cases presenting with neurological symptoms.