Primary central nervous system lymphoma in immunocompetent patients: Spectrum of findings and differential characteristics

Abstract

Primary central nervous system lymphomas (PCNSL) are rare and their management varies significantly from that of other malignant tumors involving the CNS. This article discusses how the imaging findings often suggest the diagnosis early in time. The typical findings in immunocompetent patients consist of one supratentorial intra-axial mass of homogeneous enhancement. Other findings that should be assessed include multifocality and incomplete ring enhancement. The differential diagnosis of PCNSL should mainly consider other malignant tumors of the CNS such as glioblastomas or metastases. PCNSLs tend to have less edema and less mass effect; they also tend to spare the adjacent cortex. Necrosis, hemorrhage, and calcification are rare in PCNSLs. Although the findings in the morphologic sequences are characteristic, they are not completely specific and atypical types can sometimes be found. Advanced imaging techniques such as diffusion-weighted images and, above all, perfusion-weighted images provide qualitative and quantitative data that play an important role in the differentiation of PCNSLs from other brain tumors.