Cortical Diffusion-Enhancement Mismatch Sign: A Specific Imaging Biomarker for Differentiating Primary Central Nervous System Lymphoma From Glioblastoma.

BACKGROUND AND

OBJECTIVES

Previous studies have focused on differentiating glioblastoma (GBM), isocitrate dehydrogenase-wildtype from primary central nervous system lymphoma (PCNSL) based on contrast-enhanced patterns, and/or peritumoral white matter invasion. In this study, we focused on the peritumoral area of superficially located PCNSL and GBM.

METHODS

We retrospectively reviewed the preoperative images of patients with pathologically confirmed GBM and PCNSL. The cortical diffusion-enhancement mismatch sign was defined as a high-intensity diffusion-weighted imaging lesion that involves both gray and white matters, with the corresponding gadolinium-enhanced lesion limited to the subcortical white matter, delineating the gray-white matter junction.

RESULTS

In total, 61 cases of histologically confirmed PCNSL and 65 cases of GBM were identified between August 2009 and June 2023. Thirteen cases (21.3%) of PCNSL and 35 cases (53.8%) of GBM presented with superficial lesions. Seven (53.8%) of the 13 superficial PCNSL cases presented with the cortical diffusion-enhancement mismatch sign. This sign appeared exclusively in PCNSL and was not observed in GBM (P < .001; sensitivity: 53.85%; specificity: 100%). This sign was primarily observed in diffuse large B-cell lymphoma, nongerminal center B-cell type (n = 5, 71.4%) with a mean age of 60.42 ± 15.2 years.

CONCLUSION

The cortical diffusion-enhancement mismatch sign could serve as a specific imaging diagnostic biomarker for PCNSL. This sign may suggest that PCNSL involving the cortical area developed from the white matter, not directly from the gray matter.