Diagnosis of central nervous system (CNS) non-Hodgkin's lymphomas may be difficult despite the use of sophisticated scans and routine cytologic methods. The use of an immunoalkaline phosphatase technique to examine cerebrospinal fluid (CSF) containing many mononuclear cells is described. Monoclonal proliferations of B-lymphocytes were demonstrated in six patients with neurologic abnormalities, whose clinical findings and subsequent clinical courses were those of lymphoma. The diagnosis of CNS lymphoma could not be made, despite multiple diagnostic procedures, until the immunocytochemical studies were performed. In three other patients, a lymphoproliferative disorder was suspected; however, examination of CSF showed many T-lymphocytes but no monoclonal B-lymphocytes, consistent with a reactive lymphocytosis. The subsequent clinical courses of these patients have shown no evidence of CNS lymphoma. Immunocytochemical studies of CSF lymphocytes are useful in differentiating benign from malignant proliferations.
Cancer 57:737-744, 1986.
SSESSMENT O F LYMPHOCYTOSIS in the cerebrospinal
A fluid (CSF) by conventional cytologic methods is difficult. In many instances it is impossible to differentiate benign, reactive conditions from malignant non-Hodgkin's lymphomas (NHL), even after multiple CSF samples have been examined. Immunohistochemical analysis with polyclonal antisera against kappa and lambda light chains is now commonly applied to lymph nodes to document monoclonal lymphoid proliferations in B-cell lymphomas and to demonstrate polyclonal immunostaining in benign, reactive lymphoproliferations.'" In addition, monoclonal antibodies can be used to determine the Bor T-cell nature of the lymphocytes in question, as well as T-cell sub~ets.~ We describe the application of these immunocytochemical methods to CSF to differentiate benign from malignant lymphoproliferations. These studies were performed on nine patients with CSF lymphocytosis, and