gms | German Medical Science

Joint-Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN) and the Scandinavian Neuropathological Society (SNS)

Deutsche Gesellschaft für Neuropathologie und Neuroanatomie

22.09.-24.09.2016, Hamburg

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Molecular characterization of isomorphic astrocytoma

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  • presenting/speaker Annika Kristina Wefers - Ruprecht-Karls-University Heidelberg, Institute of Pathology, Department of Neuropathology, Heidelberg, Germany
  • Ingmar Blümcke - University Hospital Erlangen, Department of Neuropathology, Erlangen, Germany
  • Roland Coras - University Hospital Erlangen, Department of Neuropathology, Erlangen, Germany
  • Andreas von Deimling - Ruprecht-Karls-University Heidelberg, Institute of Pathology, Department of Neuropathology, Heidelberg, Germany
  • Mrinalini Honavar - Hospital Pedro Hispano, Servico de Anatomia Patologica, Matosinhos, Portugal
  • Maria Thom - University College London, Institute of Neurology, Department of Neuropathology, London, United Kingdom
  • David Capper - Ruprecht-Karls-University Heidelberg, Institute of Pathology, Department of Neuropathology, Heidelberg, Germany

Deutsche Gesellschaft für Neuropathologie und Neuroanatomie. Scandinavian Neuropathological Society. Joint-Meeting of the German Society for Neuropathology and Neuroanatomy (DGNN) and the Scandinavian Neuropathological Society (SNS). Hamburg, 22.-24.09.2016. Düsseldorf: German Medical Science GMS Publishing House; 2016. Doc16dgnnP41

doi: 10.3205/16dgnn43, urn:nbn:de:0183-16dgnn434

Veröffentlicht: 14. September 2016

© 2016 Wefers et al.
Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). Lizenz-Angaben siehe http://creativecommons.org/licenses/by/4.0/.

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Introduction: Isomorphic astrocytomas (iA) are highly differentiated glial tumors with low cellularity, virtually no mitotic activity and diffuse brain infiltration. Clinically, iA are associated with long-term epilepsy and have a favorable prognosis.

Objectives: We intended to establish iA as a separate entity and characterize molecular features.

Materials & Methods: From FFPE tissue, we performed a molecular analysis of eleven iA including DNA methylation analysis, Copy number analysis and RNA sequencing (results pending).

Results: Unsupervised hierarchical clustering analysis of 450k methylation data from iA together with over 100 reference cases of established brain tumor classes (glioblastoma, astrocytoma, oligodendroglioma, angiocentric glioma, pleomorphic xanthoastrocytoma, pilocytic astrocytoma, ganglioglioma, dysembryoplastic neuroepithelial tumor and diffuse leptomeningeal glioneuronal tumor) demonstrated a close relation of iA to angiocentric glioma. Interestingly, iA form a separate group within angiocentric glioma. Many angiocentric gliomas show alterations of MYB (in particular MYB-QKI-translocations). Copy number analysis of iA also demonstrated alterations of either the MYB or MYBL1 locus in some cases. Currently we are performing RNA sequencing to further pinpoint the putative MYB/MYBL1-fusion genes of iA which may differ from those of angiocentric glioma.

Conclusion: IA may constitute an entity that is related to but clearly different from angiocentric glioma, and is also likely to have MYB/ MYBL1 alterations as a central genetic hallmark. IA constitutes a subgroup of tumors formerly diagnosed as IDH wild type diffuse astrocytomas. DNA methylation profiling may be a valuable tool to separate the generally benign iA tumors from the more malignant diffuse astrocytomas.