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Interobserver and intraobserver reproducibility in focal cortical dysplasia (malformations of cortical development)
Wendy A Chamberlain1, Mark L Cohen, Kymberly A Gyure
1Department of Anatomic Pathology, Cleveland Clinic, Cleveland, Ohio, USA.
Purpose:
Malformations of cortical development (MCD) (cortical dysplasias) are well-recognized causes of intractable epilepsy. Although a histologic classification system for MCD has been proposed by Palmini et al. (Neurology; 2004; 62:S2), studies to date have not assessed reproducibility. The purpose of this study was to analyze inter- and intraobserver agreement among eight experienced neuropathologists (NPs) with respect to this classification system.
Methods:
Sections from 26 epilepsy resections were selected to represent the range of pathologies described by Palmini et al. Recuts of single sections from each case were sent to the NPs to classify. The slides were resent at a later date for reclassification. Kappa analysis for both inter- and intraobserver concordance was performed.
Results:
Interobserver agreement was moderate (kappa = 0.4968). There was > or =62.5% (5 of 8 NPs) agreement for 19 of 26 cases. The greatest concordance was present when making focal cortical dysplasia (FCD) types IIA/B classifications (12 of the 14 cases with > or =75% consensus). Mild MCD (types I/II) and FCD types IA/B classifications were the least reproducible, and used most frequently in cases without consensus. Intraobserver concordance was moderate to very good (range kappa = 0.4654-0.8504). The category with the fewest classification changes made on reevaluation was FCD type IIB (4.2%), whereas that with the most changes was mild MCD (types I/II) (52.9%).
Discussion:
Interobserver concordance using this approach was moderate. The classification categories with the greatest concordance were FCD type IIA/B, and the least, mild MCD and FCD types IA/B. In addition, difficulty in differentiating Mild MCD/FCD type I lesions from normal and/or gliotic tissue was noted.
Insights
Reproducibility of the Palmini classification for cortical dysplasia was assessed. Agreement was moderate between neuropathologists, with better consensus for FCD types IIA/B than mild MCD or FCD types IA/B.
Area of Science:
- Neuropathology
- Epilepsy Research
- Histological Classification
Background:
- Malformations of cortical development (MCD) are significant causes of intractable epilepsy.
- A histologic classification system for MCD by Palmini et al. (2004) exists but lacks reproducibility studies.
Purpose of the Study:
- To evaluate the inter- and intraobserver agreement for the Palmini classification system among neuropathologists.
- To determine the reproducibility of classifying different types of cortical dysplasias.
Main Methods:
- Eight neuropathologists classified sections from 26 epilepsy resections representing various MCD pathologies.
- Sections were re-evaluated for intraobserver agreement, and Kappa analysis was used to assess concordance.
Main Results:
- Moderate interobserver agreement (kappa = 0.4968) was found, with 62.5% agreement for 19/26 cases.
- Focal cortical dysplasia (FCD) types IIA/B showed the highest concordance (>=75% consensus in 12/14 cases).
- Mild MCD (types I/II) and FCD types IA/B were least reproducible, with significant changes upon reevaluation (52.9% for mild MCD).
Conclusions:
- The Palmini classification system demonstrates moderate interobserver concordance.
- FCD types IIA/B are more reliably classified than mild MCD or FCD types IA/B.
- Distinguishing mild MCD/FCD type I from normal or gliotic tissue presents a challenge.
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