Radiological morphology of low-grade primary central nervous system lymphoma in immunocompetent patients

Abstract

1536 Background: Primary central nervous system lymphomas (PCNSL) are usually high-grade and very rarely low-grade non-Hodgkin’s lymphomas. They are typically contrast-enhancing lesions in contact with the subarachnoid space and without necrosis. The purpose of this study was to evaluate the radiological morphology and clinical characteristics of low-grade PCNSL. Methods: Records were reviewed from 332 patients screened for inclusion in 3 multicenter prospective trials. Ten patients (3%) with low-grade PCNSL (7 men, 3 women, median age 59 years, range 19–61 years) were identified. The pathological diagnosis of low-grade PCNSL was confirmed by a consultant hematopathologist in all patients. Brain magnetic resonance imaging (MRI) scans were obtained from all patients and centrally reviewed by two consultant neuroradiologists. Results: MRI scans were abnormal in all patients. There were 4 patients with one PCNSL manifestation, 2 with 2, and 4 with multiple manifestations. The lesions were found in the hemispheres (n = 8), basal ganglia (n = 2), corpus callosum (n = 1), and spinal cord (n = 1). Necrosis was diagnosed in only one patient. The ventricular ependyma was involved in 5 patients, one of whom had lymphoma cells in the cerebrospinal fluid. On T2-weighted images, the lesions were hyperintense in 9 patients and isointense in one patient. Nearly all lesions showed enhancement, strong in 5 and only mild to moderate in 4 patients. It was homogeneous in 4 and heterogeneous in 5 patients. Edema was moderate in 5 and marked in 4 patients. Altogether, 8 patients had a radiological morphology atypical of classical high-grade PCNSL with a subsequent false or delayed diagnosis. Conclusions: Low-grade PCNSL may have a variable and atypical radiological morphology compared to high-grade PCNSL and thus carries the risk of false or delayed diagnosis. Thus, all cases require neuropathological confirmation. No significant financial relationships to disclose.