Radiologic Morphology of Low-Grade Primary Central Nervous System Lymphoma in Immunocompetent Patients

Abstract

BACKGROUND AND PURPOSE: Primary central nervous system lymphomas (PCNSLs) are usually high-grade and are rarely low-grade non-Hodgkin lymphomas (NHLs). On MR imaging, PCNSLs typically present as contrast-enhancing lesions in contact with the subarachnoid space without evidence of necrosis. We evaluated the radiologic morphology and clinical characteristics of low-grade PCNSLs, hypothesizing that they may differ from high-grade PCNSLs.

METHODS: Records were reviewed from 332 patients screened for inclusion in 3 multicenter prospective trials. MR imaging scans were obtained from all patients and were centrally reviewed by 2 consultant neuroradiologists.

RESULTS: Ten patients (3%) with low-grade PCNSLs (7 men and 3 women; median age, 59 years; age range, 19–61 years) were identified. Four patients had one lesion, 2 patients 2 lesions, and 4 patients had multiple lesions. The following radiologic features infrequently seen in high-grade PCNSLs were found in a substantial proportion of patients: location in deep structures or spine (n=6); lack of periventricular location (n=5); hyperintensity on T2-weighted images (n=10); moderate or absent contrast enhancement (n=6); and heterogeneous contrast enhancement (n=5). In 8 patients, >2 of these features were present in at least one lesion, and, thus, the radiologic appearance was assessed atypical of high-grade PCNSLs. The atypical radiologic appearance in combination with atypical or mild symptoms resulted in a false or delayed diagnosis.

CONCLUSION: Low-grade PCNSLs may have a variable and atypical radiologic morphology compared with high-grade PCNSLs with the risk of false or delayed diagnosis.