Good interobserver and intraobserver agreement in the evaluation of the new ILAE classification of focal cortical dysplasias

Abstract

SUMMARYPurpose: An International League Against Epilepsy (ILAE) consensus classification system for focal cortical dysplasias (FCDs) has been published in 2011 specifying clinicopathologic FCD variants. The aim of the present work was to microscopically assess interobserver agreement and intraobserver reproducibility for FCD categories among an international group of neuropathologists with different levels of experience and access to epilepsy surgery tissue. Methods: Surgical FCD specimens covering a broad histopathology spectrum were retrieved from 22 patients with epilepsy. Three surgical nonepilepsy specimens served as controls. A total of 188 slides with routine or immunohistochemical stainings were digitalized with a slide scanner to allow Internet-based microscopy review. Nine experienced neuropathologists were invited to review these cases twice at a time gap of 3 months and different orders of case presentation. The 2011 ILAE FCD consensus classification served as instruction. Kappa analysis was calculated to estimate interobserver and intraobserver agreement levels. In a third evaluation round, 21 additional neuropathologists with different experience and access to epilepsy surgery reviewed the same case series.

Seizure outcome in surgically treated drug-resistant mesial temporal lobe epilepsy based on the recent histopathological classifications

“…61,70 The new classification 12 attempts to elaborate a comprehensive view of the entire group of situations in which FCD can be encountered, whether alone or in association, and it has been shown to considerably improve the reproducibility of FCD diagnosis. 21 To our knowledge, our study is the first effort to assess the impact of this new classification on surgical practice and prognosis.…”

“…14,16,86,98 In the setting of ELGT, the distinction among the various subtypes of tumors is essential for predicting the seizure outcome and the oncological behavior. In fact, gangliogliomas and dysembryoplastic neuroepithelial tumors may have pronounced intrinsic epileptogenic properties due to their neuronal and glial components, 14,21,23,[25][26][27] and their complete removal may lead to seizure freedom. With respect to oncological behavior, ELGTs are usually indolent WHO Grade I lesions, although several reports have demonstrated that gangliogliomas may potentially have an evolving course and may demonstrate malignant transformation.…”

Post-surgical outcome for epilepsy associated with type I focal cortical dysplasia subtypes

“…For instance, the histopathologic classification of these patients was decided by a sole neuropathologist. Given the interobserver variability in applying both the ILAE and the Palmini et al classification systems, 13,18 it is possible that some cases would have been classified as a different subtype by another pathologist. Second, there was somewhat inconsistent specimen processing.…”

Epilepsy Related to Developmental Tumors and Malformations of Cortical Development

“…A task force of the Diagnostic Methods Commission of the International League Against Epilepsy (ILAE) has recently generated a new consensus classification of distinct FCD subtypes based on histopathological features [6]. A recent evaluation of this classification system showed good inter-and intra-observer agreement [99], with considerable improvement compared with a previous study evaluating the 2004 Palmini FCD classification [100]. This 2011 ILAE classification consists of a three-tiered system, including both isolated and associated FCD variants [6].…”