Retrospective Brain Tumor Specimen Analysis

Formalin-fixed paraffin-embedded brain tumor resection specimens were obtained from the authors’ institutions. The cases of chordoid meningioma, chordoma and chordoid glioma were retrieved retrospectively, as well as collected prospectively. The rest of the cases were collected prospectively and date from 2014 to 2017. All meningioma cases were graded according to the 2016 WHO Classification of Tumors of the CNS [1 ]. The morphological meningioma variants were diagnosed if more than 50% of the morphologic pattern was present in the tumor [14 ]. The WHO grade II meningiomas in this study show either increased mitotic count (more or equal to 4 mitotic Figures per 10 high power fields (HPFs) by visual inspection), brain invasion, or are high risk variants (chordoid and clear cell). The other risk features of meningioma, e.g. necrosis, may or may not be present. All WHO grade III meningiomas in this study have more than 20 mitotic Figures per 10 random HPFs. The demographics include the age and gender of the patients and the location of the tumor for all cases. These studies were performed in compliance with the ethical guidelines of the Helsinki Declaration and approved by the ethical committees for research on human subjects of the authors’ institutions.