What is the Best Preoperative Quantitative Indicator to Differentiate Primary Central Nervous System Lymphoma from...

The role of surgery in primary central nervous system lymphoma (PCNSL) is to allow pathological diagnosis from tumor biopsy. However, PCNSL is often difficult to distinguish from other tumors, particularly glioblastoma multiforme (GBM). Quantitative evaluations to facilitate differentiation between PCNSL and GBM would be useful. Here, we investigated the best examinations for exact differentiation of PCNSL from GBM among preoperative examinations, including imaging studies and tumor markers.

Various examinations were performed for 68 patients with PCNSL , including serum soluble interleukin 2 receptor, β2-microglobulin (MG) in cerebrospinal fluid (CSF), diffusion-weighted imaging, ¹¹C-methionine-positron emission tomography (PET), and ¹⁸F-fluorodeoxyglucose (FDG)-PET. These results were compared with findings from 28 patients with consecutive GBM who underwent the same examinations to evaluate the utility and accuracy of different investigations.

CSF β2-MG ≥2.0 mg/L was relatively specific for PCNSL, offering 95.0% sensitivity and 85.7% specificity. Tumor-to-contralateral normal brain tissue ratio ≥2.4 on ¹⁸F-FDG-PET was also quite specific for PCNSL, offering 83.8% sensitivity and 95.2% specificity. No other examinations displayed any significant differences in quantitative differential markers between PCNSL and GBM.

Both β2-MG ≥2.0 mg/dL in CSF and tumor-to-contralateral normal brain tissue ratio ≥2.4 from ¹⁸F-FDG-PET allow quantitative differentiation of PCNSL from GBM, potentially representing clinically useful indicators. These findings could lead to innovative methods for differentiating PCNSL from GBM as well as new treatment strategies for other brain tumors.