Clinical, neuroimaging and histopathological features of gliomatosis cerebri: a systematic review based on synthesis of published individual patient data.

INTRODUCTION: Gliomatosis cerebri (GC) is a rare fatal widespread infiltrating CNS tumor. As consistent disease features have not been established, the tumor comprises a diagnostic challenge.
METHODS: We conducted a systematic literature search for published case reports and case series on patients with histologically confirmed GC. Clinical, diagnostic, neuroimaging, histopathological, and molecular data on individual or summary patient level were extracted and analyzed.
RESULTS: A total of 274 studies were identified, including 866 patients with individual-level data and 782 patients with summary data (58.9% males, mean age 43.6 years). Seizures (49.8%) were the most common presenting symptom followed by headache (35.9%), cognitive decline (32.2%), and focal motor deficits (32%). Imaging studies showed bilateral hemisphere involvement in 65%, infratentorial infiltration in 29.9% and a focal contrast-enhanced mass (type II GC) in 31.1% of cases. MRI (extensive hyperintensities in T2/FLAIR sequences) and MR spectroscopy (elevated choline, creatinine, and myoinositol levels; decreased NAA levels) showed highly consistent findings across GC patients. Low-grade and anaplastic astrocytoma were the most prevalent diagnostic categories, albeit features of any histology (astrocytic, oligodendroglial, oligoastrocytic) and grade (II-IV) were also reported. Among molecular aberrations, IDH1 mutation and MGMT promoter methylation were the most commonly reported. Increasing time elapsed from symptom onset to diagnosis comprised the only independent determinant of the extent of CNS infiltration.
CONCLUSION: A distinct clinical, neuroimaging, histopathological, or molecular GC phenotype is not supported by current evidence. MRI and MR spectroscopy are important tools for the diagnosis of the tumor before confirmation with biopsy.