Primary CNS lymphoma - A whole-brain disease?

Background: Autopsy studies reveal that most primary CNS lymphomas (PCNSL) extensively infiltrate the brain. To date, there has been no correlation of autopsy findings with a modern neuroimaging assessment of tumor burden. Objective: To correlate autopsy findings in PCNSL to MRI findings. Method: From the authors' database of immunocompetent patients with PCNSL diagnosed between 1985 and 2001, 10 patients who died and had PCNSL at autopsy were identified. Their pathology was compared to MR scans obtained shortly before death. Results: The median patient age was 60 years (range 44 to 80 years). There were six men and four women. Scans were performed within 4 weeks of death in seven patients, within 3 months in two patients, and within 4 months in one. Seven had enhancing lesions consistent with recurrence, and two of the three had focal T2 abnormalities. All had periventricular white matter abnormalities on T2 MR images. At autopsy, all 10 patients had widespread lymphoma throughout the CNS, but no tumor was found systemically. All had tumor infiltration in CNS regions that were normal radiographically, including T2 sequences. Conclusions: MRI underestimates the tumor,burden of PCNSL. Bulky disease is seen as a contrast-enhancing lesion because of disruption of the blood-brain barrier, but microscopic tumor infiltration may lead to T2 hyperintensity or be completely normal radiographically.