CSF analysis of IgH gene rearrangement in CNS lymphoma: Relationship to the disease course

Purpose: To assess whether clonal IgH genes in CSF of patients with CNS lymphoma correlates with the disease course. Background: It has been shown that the PCR technique, which offers a sensitive test for diagnosis of systemic lymphoproliferative malignancies, can be applied to the CSF. Methods: Seventy-three CSF specimens from 32 patients (27 with primary CNS lymphoma and 5 with an isolated parenchymal CNS relapse of systemic lymphoma) were examined. The results were evaluated retrospectively and compared to conventional cytology, clinical and imaging data, and course of the disease. CNS disease was defined as active when leptomeningeal and/or parenchymal brain involvement was evident on neuroimaging. Patients were considered to have a complete response when imaging confirmed absence of a tumor mass or leptomeningeal seeding. Results: Sixty-three of 73 samples had adequate genetic material for testing. Of the 63, 15 (24%) were positive for clonal IgH rearrangement. In nine (60%) of the 15 patients with active disease, PCR results were positive, while negative results were observed in 19 (95%) of the 20 patients showing clear response to treatment. The sensitivity and specificity of the PCR evaluation were 54% and 97%, respectively. The predictive values of positive and negative tests were 93% and 74%, respectively. Conclusions: The integrated results of both PCR and cytology evaluations increase the sensitivity of CSF analysis. The PCR study has high specificity and positive results are indicative for the presence of active disease, even when the tumor seems confined to the brain parenchyma.