Oligosarcomas, IDH-mutant are distinct and aggressive.

Abstract

Oligodendrogliomas are defined at the molecular level by the presence of an IDH mutation and codeletion of chromosomal arms 1p and 19q. In the past, case reports and small studies described gliomas with sarcomatous features arising from oligodendrogliomas, so called oligosarcomas. Here, we report a series of 24 IDH-mutant oligosarcomas from 23 patients forming a distinct methylation class. The tumors were recurrences from prior oligodendrogliomas or developed de novo. Precursor tumors of 12 oligosarcomas were histologically and molecularly indistinguishable from conventional oligodendrogliomas. Oligosarcoma tumor cells were embedded in a dense network of reticulin fibers, frequently showing p53 accumulation, positivity for SMA and CALD1, loss of OLIG2 and gain of H3K27 trimethylation (H3K27me3) as compared to primary lesions. In 5 oligosarcomas no 1p/19q codeletion was detectable, although it was present in the primary lesions. Copy number neutral LOH was determined as underlying mechanism. Oligosarcomas harbored an increased chromosomal copy number variation load with frequent CDKN2A/B deletions. Proteomic profiling demonstrated oligosarcomas to be highly distinct from conventional CNS WHO grade 3 oligodendrogliomas with consistent evidence for a smooth muscle differentiation. Expression of several tumor suppressors was reduced with NF1 being lost frequently. In contrast, oncogenic YAP1 was aberrantly overexpressed in oligosarcomas. Panel sequencing revealed mutations in NF1 and TP53 along with IDH1/2 and TERT promoter mutations. Survival of patients was significantly poorer for oligosarcomas as first recurrence than for grade 3 oligodendrogliomas as first recurrence. These results establish oligosarcomas as a distinct group of IDH-mutant gliomas differing from conventional oligodendrogliomas on the histologic, epigenetic, proteomic, molecular and clinical level. The diagnosis can be based on the combined presence of (a) sarcomatous histology, (b) IDH-mutation and (c) TERT promoter mutation and/or 1p/19q codeletion, or, in unresolved cases, on its characteristic DNA methylation profile.

• Authors: Abigail K Suwala, Marius Felix, Dennis Friedel, Damian Stichel, Daniel Schrimpf, Felix Hinz, Ekkehard Hewer, Leonille Schweizer, Hildegard Dohmen, Ute Pohl, Ori Staszewski, Andrey Korshunov, Marco Stein, Thidathip Wongsurawat, Pornsuk Cheunsuacchon, Sith Sathornsumetee, Christian Koelsche, Clinton Turner, Emilie Le Rhun, Angelika Mühlebner, Philippe Schucht, Koray Özduman, Takahiro Ono, Hiroaki Shimizu, Marco Prinz, Till Acker, Christel Herold-Mende, Tobias Kessler, Wolfgang Wick, David Capper, Pieter Wesseling, Felix Sahm, Andreas von Deimling, Christian Hartmann, David E Reuss
• Journal: Acta neuropathologica (Acta Neuropathol) Vol. 143 Issue 2 Pg. 263-281 (02 2022) ISSN: 1432-0533 [Electronic] Germany
• PMID: 34967922 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2021. The Author(s).

Chemical References

• Isocitrate Dehydrogenase

Topics

• Adult
• Aged
• Brain Neoplasms (genetics, pathology)
• Female
• Humans
• Isocitrate Dehydrogenase (genetics)
• Male
• Middle Aged
• Mutation
• Oligodendroglioma (genetics, pathology)
• Sarcoma (genetics, pathology)