Vet Comp Oncol. 2022 Jan 23. doi: 10.1111/vco.12802. Online ahead of print.
ABSTRACT
The human grading system is currently applied to canine meningioma, although it has not been validated in dogs. The present study focused on standardizing the human grading system applied to canine meningioma. Four veterinary neuropathologists graded 186 canine meningiomas as follows: grade I tumor, with <4 mitoses/2.37 mm2 ; grade II tumor, with ≥4 mitoses/2.37 mm2 , brain invasion or at least 3 of the following criteria: sheeting architecture, hypercellularity, small cells, macronucleoli, necrosis; grade III tumor, with ≥20 mitoses/2.37 mm2 or anaplasia. Slides with grading disagreement were reviewed to define a consensus diagnosis and to assess reproducible criteria. Concordance between histologic grade and the consensus diagnosis, as well as intra- and inter-observer agreements for each criterion, were statistically analyzed. Concordance between histologic grade and consensus diagnosis ranged from 59% to 100%, with lower concordance for grade I and II tumors. The lowest inter-observer agreement was recorded for macronucleoli, small cells, hypercellularity and sheeting architecture. Tumor invasion and necrosis displayed fair agreement, while moderate agreement was reached for mitotic grade and anaplasia. The following recommendations were issued to improve reproducibility of canine meningioma grading: 1. Assess mitotic grade in consecutive HPFs within the most mitotically active area; 2. Define invasion as neoplastic protrusions within central nervous tissue without pial lining; 3. Report spontaneous necrosis; 4. Report prominent nucleoli when visible at 100x; 5. Report pattern loss when visible at 100x in > 50% of the tumor; 6. Report necrosis, small cells, hypercellularity and macronucleoli, even when focal; 7. Report anaplasia if multifocal. This article is protected by copyright. All rights reserved.
PMID:35066998 | DOI:10.1111/vco.12802
