Abstract 18
Category: Clinical Science
At the end of the session, participants will be able to:
- Describe the methods of grading and prognostication for meningiomas.
- Understand the strengths and limitations of methylation classification in meningioma prognostication
- Integrate histology, methylation classification, and copy-number profiling for meningioma prognostication.
COI Disclosure:
None to disclose.
Presenter
Shane Eaton is a PGY4 resident in Neuropathology at the University of Toronto.
Shane Eaton1, Robert Siddaway2, Anthony Arnoldo3, Arun Vadivel3, Adrian Levine1,4, Cynthia Hawkins1,4
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.
- Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, Canada.
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, ON, Canada.
- Department of Pathology, The Hospital for Sick Children, Toronto ON, Canada.
Target Audience:
Pathologists, Residents
CanMEDS:
Medical Expert (the integrating role), Communicator
Abstract
DNA methylation patterns have emerged as a useful signature for classifying brain tumours. These patterns tend to be consistent within tumour entities and even within subtypes, and have proved to be a helpful tool in resolving diagnostically challenging cases. However, methylation classification is not always reliable. In particular, in light of the recent cIMPACT-NOW guidelines for meningioma prognostication, inconsistencies have appeared between the prognostic subtypes defined by methylation profiling and the grading recommended on the basis of copy number profiles.
To explore this, we reviewed methylation results from cases at SickKids Hospital, focusing on areas of concordance and discordance. From 841 total methylation cases, 46 were meningiomas. Within this group 13% showed discordant prognostication between methylation subtyping and the copy number-based stratification described in cIMPACT-NOW update 8. We present several illustrative cases to highlight when methylation was useful, when it led to conflicting results, and the factors contributing to the discordance.
Previous studies have suggested a multi-factorial approach to meningioma gradin and prognostication underscored by our results. How to approach grading in the setting of discordant findings will require further study with well annotated clinical outcome data. While methylation can be a powerful diagnostic adjunct, these results caution against overreliance on this method alone for meningioma classification and prognostication.