Category: Basic Science
At the end of the session, participants will be able to:
- Compare the prevalence of atypical mitoses in meningiomas based on tumour grade
COI Disclosure:
None to disclose
Presenter
Tracy Wang is a 3rd year medical student currently attending the Schulich School of Medicine at Western University.
Tracy Wang 1, Jacob A. Houpt 2, Eric Liu 3, Qi Zhang 2
1Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
2Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada
3Department of Computer Science, Western University, London, ON, Canada
Target Audience:
CanMEDS:
The prognostic value of atypical mitotic figures in meningiomas
Abstract
Presently, the mitotic count for WHO grading of meningiomas does not distinguish between normal and atypical mitoses. However, atypical mitoses have been associated with poorer prognosis in pancreatic and breast carcinomas. This research aims to identify whether such an association also exists for meningiomas. Whole slide images were retrieved from the Digital Brain Tumour Atlas (Sci Data 2022;9:55). The meningothelial, atypical, and anaplastic categories were used to represent grade 1-3 meningiomas respectively. Each slide was annotated for normal and atypical mitotic counts using AI4Path software, and annotations were confirmed by expert reviewer. Types of atypical mitoses were defined by studies such as Lashen et al. (2022), including multipolar, chromatin-bridging, etc. Mitotic counts were normalized to tissue surface area, and statistical analysis performed using one-way ANOVA and post-hoc Tukey’s HSD. Preliminary findings from 30 meningiomas (10 of each grade) showed a total of 3083 mitotic figures, 336 of which were atypical. There was a statistically significant difference in the number of atypical mitoses in grade 3 meningiomas compared to grade 1 (p<0.001) and grade 2 (p<0.001). The ratio of atypical-to-normal mitoses was not statistically significant between grades, but this may reflect the low total number of mitoses in grade 1 tumours. Current histopathological criteria to diagnose grade 3 meningiomas include a mitotic rate ≥20 mitotic figures/10hpf and frank anaplasia. These findings suggest that atypical mitotic count has the potential to provide another useful diagnostic criterion in the future. Next steps include incorporating additional cases and more detailed clinical information.