The New WHO Classification and the Role of Integrated Molecular Profiling in the Diagnosis of Malignant Gliomas Stefan Prokop, MD Neuropathology Fellow Hospital of the University of Pennsylvania
Background Updated WHO in 2016 Incorporates Layered Diagnoses Histology Immunohistochemical markers Molecular WHO grade Re-classifies certain tumors and tumor groups
Glial neoplasms: Infiltrating Gliomas then (2007 WHO classification) Astrocytic tumors Diffuse astrocytoma Anaplastic astrocytoma Glioblastoma Giant cell glioblastoma Gliosarcoma Oligoastrocytic tumors Oligoastrocytoma Anaplastic oligoastrocytoma Oligodendroglial tumors Oligodendroglioma Anaplastic oligodendroglioma
Photo courtesy of Dr. Edward B. Lee Oligodendrogliomas Fried egg appearance Chicken wire capillaries Micro-califications Microcystic Gemistocytic tumor cells
Photo courtesy of Aivi T. Nguyen Astrocytomas Hypercellularity Nuclear atypia +/- Mitotic activity No necrosis No microvascular proliferation
Photo courtesy of Aivi T. Nguyen Astrocytomas: Glioblastoma Atypia Necrosis Pseuodpalisading Geographic Microvascular proliferation Vessel thromboses
Photo courtesy of Aivi T. Nguyen Astrocytomas: Glioblastoma Atypia Necrosis Pseuodpalisading Geographic Microvascular proliferation Vessel thromboses
Molecular Landscape of Gliomas
Isocitrate dehydrogenase (IDH) mutations in gliomas Yan et al., NEJM 2009
IDH: Isocitrate Dehydrogenase mutations in tumors Presner et al., Nature Med, 2011
Prognostic impact of IDH mutation status IDH1-mutation specific antibody Hartmann et al., Acta Neuropathologica 2010
Concurent 1p and 19q chromosome loss in Oligodendrogliomas lost Whole-arm translocation Weller et al., Neuro-Oncology 2014 - Initially shown to be associated with better prognosis in diffuse gliomas Griffin et al., Journal of Neuropathology and Experimental Neurology 2006 - Co-occurrence of 1p/19q deletion and IDH mutation defines Oligodendrogliomas
Glial neoplasms: Infiltrating Gliomas now (2016 WHO classification) Astrocytic tumors Diffuse astrocytoma Anaplastic astrocytoma Glioblastoma Giant cell glioblastoma Gliosarcoma Oligodendroglial tumors Oligodendroglioma Anaplastic oligodendroglioma Oligoastrocytic tumors Oligoastrocytoma Anaplastic oligoastrocytoma Integrated diagnosis incorporating histology, immunohistochemistry and molecular findings to define tumor entities
Glial neoplasms: Infiltrating Gliomas now (2016 WHO classification) Astrocytic tumors Diffuse astrocytoma Anaplastic astrocytoma Glioblastoma Giant cell glioblastoma Gliosarcoma IDH wild type or IDH mutant 1p/19q non co-deleted Oligodendroglial tumors Oligodendroglioma Anaplastic oligodendroglioma IDH mutant and 1p/19q co-deleted (entity defining genetic alterations)
Louis et al., Acta Neuropathologica 2016
Mutations of Selected Genes in Glioma Subtypes Glioblastoma Astrocytoma Oligodendroglioma Oligoastrocytoma Killela et al., PNAS 2013
The New WHO Classification in Action
WHO 2016: Layered Diagnosis Integrated Diagnosis Incorporating all aspects of tissue diagnosis Histological Classification WHO Grade reflects natural history, based on histology Molecular information Louis et al., Brain Pathology 2014
Workflow Histology H&E sections Tissue is processed (formalin fixation) and put on slides Review slides and immunostains, write pathology report Molecular Molecular tests ordered CPD, EGFRvIII, MGMT promoter methylation tests ordered after sign out of case Integrated Diagnosis Molecular results Results returned ~2 weeks Integrated diagnosis in addendum (no longer pending )
Example: Histology Photos courtesy of Dr. Edward B. Lee
Example: Initial Diagnosis Integrated diagnosis: Pending Histologic diagnosis: Infiltrating high grade glioma Histologic grade: At least WHO grade III Molecular information: Pending
Example: Final Diagnosis Integrated diagnosis: Pending Histologic diagnosis: Infiltrating high grade glioma Histologic grade: At least WHO grade III Molecular information: Pending Integrated diagnosis: Glioblastoma, IDH-wildtype, WHO grade IV Histologic diagnosis: Glioblastoma Histologic grade: WHO grade IV Molecular information: IDH negative, 1p/19q-intact
Example: Final Diagnosis Integrated diagnosis: Pending Histologic diagnosis: Infiltrating high grade glioma Histologic grade: At least WHO grade III Molecular information: Pending Integrated diagnosis: Glioblastoma, IDH-mutant, WHO grade IV Histologic diagnosis: Glioblastoma Histologic grade: WHO grade IV Molecular information: IDH p.r132h positive, 1p/19q-intact
Example: Final Diagnosis Integrated diagnosis: Pending Histologic diagnosis: Infiltrating high grade glioma Histologic grade: At least WHO grade III Molecular information: Pending Integrated diagnosis: Anaplastic Oligodendroglioma, IDH-mutant, 1p/19qcodeleted, WHO grade III Histologic diagnosis: Oligodendroglioma Histologic grade: WHO grade III Molecular information: IDH p.r132h, 1p/19q-codeleted
Three different diagnoses Glioblastoma - 1 IDH-wildtype IDH1 (R132H) negative CPD negative 1p/19q-intact Glioblastoma - 2 IDH-mutant IDH1 (R132H) positive IDH1 p.r132h 1p/19q-intact Anaplastic Oligo. IDH-mutant IDH1 (R132H) positive IDH1 p.r132h 1p/19q-codeleted
Do we need a microscope? Yes! Must make histological diagnosis of glioma first WHO grade is based mainly on histology Some gliomas do not have these diagnostic genetic changes
Simplified algorithm for classification of diffuse gliomas based on histology and genetics More genetic changes will be found. Louis et al., Acta Neuropathologica 2016 27
Summary Integration of molecular and histologic findings improves the definition of tumor entities Molecular profiling of gliomas and glioma subtypes will guide targeted and personalized therapeutic approaches
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow
Neuro-Oncology Molecular testing workflow