Interobserver and intraobserver reproducibility in focal cortical dysplasia (malformations of cortical development)

Department of Anatomic Pathology, Cleveland Clinic, Cleveland, Ohio, USA.
Epilepsia (Impact Factor: 4.57). 10/2009; 50(12):2593-8. DOI: 10.1111/j.1528-1167.2009.02344.x
Source: PubMed


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.
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.
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%).
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.

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Available from: Wendy Ann Chamberlain, Dec 11, 2015
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    • "It was revisited by an ILAE Task Force in 2011, for the reason that some histopathology definitions of FCD subtypes were not proven reliable. As a prominent example, in an agreement study among nine North American neuropathologists , least agreement was achieved when judging Palmini FCD type Ib, reflecting the challenge to properly distinguish this subtype from normal cortical tissue (Chamberlain et al., 2009). It was the consensus of the ILAE Task Force to propose a classification system relying on careful histopathologic evaluation, giving at hand a microscopic description of histology features to better distinguish FCD subtypes. "

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    • "The prevalence of pharmacoresistant epilepsy in NF1 is low and the number of patients undergoing surgical treatment, and histopathological studies , is consequently small (0.5% of all epilepsy surgery cases in our study). Interobserver concordance among neuropathologists was high (10 of 12 patients), when compared to previous reports on intra and interobserver reproducibility in the classification of dysplastic lesions (Chamberlain et al., 2009) and brain tumours (Gilles et al., 2008), The only two discordant diagnoses might be related to different classification attitudes among neuropathologists (Chamberlain et al., 2009; Gilles et al., 2008). Sixty-six percent of our patients were cognitively impaired. "
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    ABSTRACT: Epilepsy is relatively uncommon in patients with Neurofibromatosis Type 1 (NF1) and seizures are usually well controlled with antiepileptic treatment. However, pharmacoresistance has been reported in patients with NF1 and MRI evidence of malformations of cortical development or glioneuronal tumours. Available information on epilepsy surgery in NF1 is limited to a few patients with gliomas and glioneuronal tumours who underwent lesionectomies. We conducted a survey amongst 25 European epilepsy surgery centres to collect patients with NF1 who had undergone surgery for drug-resistant seizures and identified 12 patients from eight centres. MRI abnormalities were present in all patients but one. They were unilateral temporal in eight, bilateral temporal in one and multilobar or hemispheric in two. Seizures originated from the temporal lobe in ten patients, from the temporo-parieto-occipital region in one, and were bitemporal in one. One year after surgery eight patients were seizure free, one had worthwhile improvement and the remaining three had experienced no benefit. Postoperative outcome, available at 2 years in ten patients and at 5 years in three, remained stable in all but one whose seizures reappeared. Histology revealed dysembryoplastic neuroepithelial tumour (DNET) in five patients, hippocampal sclerosis in four, mixed pathology in one and polymicrogyria in one. No histological abnormality was observed in the remaining patient. Epilepsy surgery can be performed effectively in patients with NF1 provided a single and well-delimited epileptogenic zone is recognized. The high prevalence of DNETs in this series might suggest a non-fortuitous association with NF1.
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    • "According to Palmini’s system, the radiologic characteristics of FCD may be diverse even within a given subtype.6,7 Moreover, histologic examination cannot guarantee reliability in diagnosis, particularly when the FCD pathology is mild.8 "
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    ABSTRACT: Malformation of cortical development (MCD) is a well-known cause of drug-resistant epilepsy and focal cortical dysplasia (FCD) is the most common neuropathological finding in surgical specimens from drug-resistant epilepsy patients. Palmini's classification proposed in 2004 is now widely used to categorize FCD. Recently, however, Blumcke et al. recommended a new system for classifying FCD in 2011. We applied the new classification system in practical diagnosis of a sample of 117 patients who underwent neurosurgical operations due to drug-resistant epilepsy at Severance Hospital in Seoul, Korea. Among 117 cases, a total of 16 cases were shifted to other FCD subtypes under the new classification system. Five cases were reclassified to type IIIa and five cases were categorized as dual pathology. The other six cases were changed within the type I category. The most remarkable changes in the new classification system are the advent of dual pathology and FCD type III. Thus, it will be very important for pathologists and clinicians to discriminate between these new categories. More large-scale research needs to be conducted to elucidate the clinical influence of the alterations within the classification of type I disease. Although the new FCD classification system has several advantages compared to the former, the correlation with clinical characteristics is not yet clear.
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