Advantages of flow cytometry immunophenotyping for the diagnosis of central nervous system non-Hodgkin's lymphoma in AIDS patients

Abstract

Background: Neurological disorders are common in HIV-infected patients. Central nervous system (CNS) lymphoma should always be considered because it is an important cause of morbidity and mortality. Objectives: To investigate the clinical utility of flow cytometry immunophenotyping (FCI) in diagnosing or discarding leptomeningeal involvement in HIV-infected patients and to compare its sensitivity with that of conventional cytological methods. Methods: Fifty-six cerebrospinal fluid (CSF) samples from 29 HIV-infected patients were independently evaluated by flow cytometry and cytology. The description of an aberrant immunophenotype was the criterion used to define the malignant nature of any CSF cell population. Results: FCI and cytology gave concordant results for 48 of the 56 CSF samples studied: 37 were negative for malignancy and 11 had evidence of CNS lymphoma. Discordant results were obtained for eight CSF samples, and the accuracy of the FCI findings could be demonstrated for four CSF samples described as positive for malignancy according to the FCI criteria. Conclusions: A high level of agreement was found between the results obtained using the two methods, but FCI gave at least 25% higher sensitivity than conventional cytomorphological methods for the detection of malignant cells. This advantage suggests that, in case of negative flow cytometry results, disorders other than non-Hodgkin's lymphoma should be strongly considered. © 2005 British HIV Association.