The role of frameless stereotactic biopsy in contemporary neuro-oncology: molecular specifications and diagnostic yield in biopsied glioma patients

INTRODUCTION: With the 2016 World Health Organization Classification of Tumors of the Central Nervous System (2016 CNS WHO), diagnosis of glioma is based on molecular parameters in addition to histology potentially leading to additional demands on quality of tissue samples. This may challenge the role of minimally invasive biopsy procedures. This study aims to evaluate the diagnostic yield of glioma samples from frameless stereotactic biopsies with focus on molecular information and explore the neuromolecular profile of a glioma biopsy cohort.

METHODS: In a case series analysis, 180 consecutive frameless stereotactic biopsies with the Brainlab® Varioguide system from January 2011 to October 2017 were reviewed and patients with suspected or verified glioma were identified. Neuropathological samples were reprocessed in accordance with 2016 CNS WHO standards.

RESULTS: One hundred nineteen glioma patients were identified. Analysis of IDH status could be performed in 95.8% resulting in a cumulative mutation rate of 9.6%. A complete diagnosis according to 2016 CNS WHO including grading and molecular features was achieved in 110 cases (92.4%). Entities were revised in four cases. Most common diagnosis was IDH-wildtype glioblastoma (66.4%) followed by IDH-wildtype anaplastic astrocytoma (21.8%).

CONCLUSIONS: A formally complete diagnosis according to 2016 CNS WHO was achieved in the majority of cases. The biopsy cohort showed a prognostically unfavorable distribution of diagnoses and molecular features. Frameless stereotactic biopsy seems to be confirmed as a useful diagnostic tool in contemporary neuro-oncology-however, certain potential limitations should be considered.