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

BACKGROUND: The role of surgery in primary central nervous system lymphoma (PCNSL) is to allow pathological diagnosis from tumor biopsy. However, PCNSL is often diffi-cult to distinguish from other tumors, particularly glioblas-toma multiforme (GBM). Quantitative evaluations to facilitate differentiation between PCNSL and GBM would be useful. Here, we investigated the best examinations for exact dif-ferentiation of PCNSL from GBM among preoperative exami-nations, including imaging studies and tumor markers.-METHODS: Various examinations were performed for 68 patients with PCNSL , including serum soluble interleukin 2 receptor, 02-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.-RESULTS: CSF 02-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 exami-nations displayed any significant differences in quantita-tive differential markers between PCNSL and GBM.-CONCLUSIONS: Both 02-MG >= 2.0 mg/dL in CSF and tu-mor-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.

Automated summary

PCNSL and GBM can be accurately differentiated through various examinations, including measurements of serum soluble interleukin-2 receptor and 02-microglobulin in cerebrospinal fluid, as well as imaging studies and tumor markers. The concentrations of 02-microglobulin in CSF ≥2.0 mg/L and tumor-to-contralateral normal brain tissue ratio ≥2.4 on 18F-FDG-PET can quantitatively differentiate PCNSL from GBM, which may serve as clinically useful indicators.