[Leptomeningeal dissemination of chronic lymphatic leukemia. Molecular genetic detection in cerebrospinal fluid].

The diagnosis of leptomeningeal dissemination of chronic lymphatic leukemia (CLL) by conventional cytology is unreliable because cytomorphologic criteria of malignancy are often lacking. Immunophenotyping of leukocyte differentiation antigens may also be of limited diagnostic value due to the small number of cells in cerebrospinal fluid (CSF) samples. Molecular methods may support the specific diagnosis of leptomeningeal infiltration of CLL. We present an 54 old patient who was diagnosed with CLL five years ago. Despite clinical signs of leptomeningeal involvement neither magnetic resonance imaging (MRI) nor conventional CSF analysis were suggestive of lymphomatous meningitis. Using PCR we selectively amplified the highly variable and clone-specific CDR3 region of the locus encoding the immunoglobulin heavy chain (IgH) in DNA obtained from both CSF and peripheral blood cells. Analysis of PCR products by high resolution gel electrophoresis revealed a single DNA fragment respectively indicating the presence of a monoclonal cell population in both compartments. DNA sequence analysis of the amplified CDR3 segments confirmed the clonal identity of cells and the leptomeningeal dissemination of CLL.