title: Histologic classification of gliomas.
abstract: Gliomas form a heterogeneous group of tumors of the central nervous system (CNS) and are traditionally classified based on histologic type and malignancy grade. Most gliomas, the diffuse gliomas, show extensive infiltration in the CNS parenchyma. Diffuse gliomas can be further typed as astrocytic, oligodendroglial, or rare mixed oligodendroglial-astrocytic of World Health Organization (WHO) grade II (low grade), III (anaplastic), or IV (glioblastoma). Other gliomas generally have a more circumscribed growth pattern, with pilocytic astrocytomas (WHO grade I) and ependymal tumors (WHO grade I, II, or III) as the most frequent representatives. This chapter provides an overview of the histology of all glial neoplasms listed in the WHO 2016 classification, including the less frequent "nondiffuse" gliomas and mixed neuronal-glial tumors. For multiple decades the histologic diagnosis of these tumors formed a useful basis for assessment of prognosis and therapeutic management. However, it is now fully clear that information on the molecular underpinnings often allows for a more robust classification of (glial) neoplasms. Indeed, in the WHO 2016 classification, histologic and molecular findings are integrated in the definition of several gliomas. As such, this chapter and Chapter 6 are highly interrelated and neither should be considered in isolation.
authors.affiliation: Departments of Pathology and Neurological Surgery, University of California San Francisco, San Francisco, CA, USA. Electronic address: arie.perry@ucsf.edu.
authors.forename: Arie
authors.initials: A
authors.lastname: Perry
authors.affiliation: Department of Pathology, VU University Medical Center, Amsterdam, Department of Pathology, Canisius Wilhelmina Hospital, Nijmegen, and Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Wesseling
mesh_terms: D001932:Brain Neoplasms / Q000145:classification* / Q000473:pathology*; D005910:Glioma / Q000145:classification* / Q000473:pathology*; D006652:Histological Techniques / Q000379:methods*; D006801:Humans
keywords: astrocytoma; ependymoma; glioblastoma; glioma; glioneuronal tumor; histopathology; immunohistochemistry; molecular diagnostics; neuropathology; oligodendroglioma