Inter‐pathologist agreement on diagnosis, classification and grading of canine glioma

Abstract

Histopathological evaluation of tumours is a subjective process, but studies of inter‐pathologist agreement are uncommon in veterinary medicine. The Comparative Brain Tumour Consortium (CBTC) recently published diagnostic criteria for canine gliomas. Our objective was to assess the degree of inter‐pathologist agreement on intracranial canine gliomas, utilising the CBTC diagnostic criteria in a cohort of eighty‐five samples from dogs with an archival diagnosis of intracranial glioma. Five pathologists independently reviewed H&E and immunohistochemistry sections and provided a diagnosis and grade. Percentage agreement and kappa statistics were calculated to measure inter‐pathologist agreement between pairs and amongst the entire group. A consensus diagnosis of glioma subtype and grade was achieved for 71/85 (84%) cases. For these cases, percentage agreement on combined diagnosis (subtype and grade), subtype only and grade only were 66%, 80% and 82%, respectively. Kappa statistics for the same were 0.466, 0.542 and 0.516, respectively. Kappa statistics for oligodendroglioma, astrocytoma and undefined glioma were 0.585, 0.566 and 0.280 and were 0.516 for both low‐grade and high‐grade tumours. Kappa statistics amongst pairs of pathologists for combined diagnosis varied from 0.352 to 0.839. 8 % of archival oligodendrogliomas and 61% of archival astrocytomas were reclassified as another entity after review. Inter‐pathologist agreement utilising CBTC guidelines for canine glioma was moderate overall but varied from fair to almost perfect between pairs of pathologists. Agreement was similar for oligodendrogliomas and astrocytomas but lower for undefined gliomas. These results are similar to pathologist agreement in human glioma studies and with other tumour entities in veterinary medicine.

Standardization of canine meningioma grading: Validation of new guidelines for reproducible histopathologic criteria

“…For the histologic grade, application of the guidelines resulted in an increased inter‐observer agreement shown by the kappa index, which shifted from 0.41 to 0.52. The improved agreement is comparable to that obtained in veterinary medicine with other grading systems and tumours (for gliomas κ = 0.5 19 ; for canine soft tissue sarcoma κ = 0.43 20 ). Nevertheless, this result is below the agreement obtained for human meningioma ( κ = 0.71–0.84, depending on tumour grade) 12 .…”

“…A reproducible and reliable grading system is necessary to correlate histologic findings with prognosis in both human medicine [12][13][14][15][16][17] and veterinary medicine. [18][19][20][21] The reproducibility of the human meningioma grading system applied to canine meningioma was previously investigated to lay the groundwork for studies on the prognostic significance of histologic grade in canine meningiomas. Use of the human grading system to grade canine meningiomas resulted in low reproducibility, possibly due to unclear descriptions of some of the diagnostic criteria in the veterinary literature.…”

“…A reproducible and reliable grading system is necessary to correlate histologic findings with prognosis in both human medicine 12–17 and veterinary medicine 18–21 . The reproducibility of the human meningioma grading system applied to canine meningioma was previously investigated to lay the groundwork for studies on the prognostic significance of histologic grade in canine meningiomas.…”

Standardization of canine meningioma grading: validation of new guidelines for reproducible histopathologic criteria

“…For the histologic grade, application of the guidelines resulted in an increased inter-observer agreement shown by the kappa index, which shifted from 0.41 to 0.52. The improved agreement is comparable to that obtained in veterinary medicine with other grading systems and tumours (for gliomas κ = 0.519 ; for canine soft tissue sarcoma κ = 0.4320 ). Nevertheless, this result is below theF I G U R E 7 Spontaneous necrosis.…”

An Illustrated Scoping Review of the Magnetic Resonance Imaging Characteristics of Canine and Feline Brain Tumors

“…Should semiquantitative gradations of contrast enhancement be derived from the volume of enhancing tissue or the relative signal intensity of the enhancement? There also exists the possibility for lesion misclassification errors in multiple studies, particularly in relation to tumor typing and grading, as interobserver variability, even among experienced neuropathologists, is a well-recognized phenomenon [66,69,70,89]. These factors could contribute to the inability to identify specific and significant imaging variables associated with tumor type or grade across different studies.…”