REVIEW article
Front. Cell. Neurosci.
Sec. Non-Neuronal Cells
This article is part of the Research TopicNeuronal and glial studies in human brain tissue: research perspectives and ethical considerationsView all articles
Architecture and cellular composition of Focal Cortical Dysplasia type II: qualitative review of histological studies
Provisionally accepted
- 1Institut Imagine Institut des Maladies Genetiques, Paris, France
- 2Institut de Psychiatrie et Neurosciences de Paris, Paris, France
- 3Groupe Hospitalier Universitaire Paris psychiatrie & neurosciences Pole Neuro Sainte-Anne, Paris, France
- 4Hopital Universitaire Necker-Enfants Malades Service de Neurochirurgie, Paris, France
- 5Universite Paris Cite, Paris, France
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Focal cortical dysplasia (FCD) is a malformation of cortical development strongly associated with drug-resistant epilepsy, particularly in children but also observed in adults. FCD type II is specifically characterised by cortical disorganisation and the presence of abnormal cells. This condition has been widely linked to hyperactivation of the mTOR signalling pathway, secondary to somatic mutations. After five decades of research, the comprehensive understanding of FCD architecture remains incomplete, with significant variability across studies, influenced by differences in tissue samples, cohort characteristics, and experimental protocols. This review aims to synthesise current knowledge on FCD architecture to clarify how the cerebral cortex is altered in FCD. We particularly focus on the hallmarks of FCD: cortical dislamination, balloon cells and dysmorphic neurons. Additionally, we explore recent insights into the composition of cortical neuronal populations, emphasising the role of inhibitory interneuron populations, which have gained attention following discoveries regarding the involvement of GABAergic signalling in epileptogenesis. Overall, our review highlights key considerations for future single-cell and spatial studies aimed at minimising sampling bias.
Keywords: focal cortical dysplasia, Dislamination, Balloon cells, Dysmorphic neurons, Interneurons
Received: 18 Sep 2025; Accepted: 21 Nov 2025.
Copyright: © 2025 Castaño-Martín, Metais, Ciura and Blauwblomme. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Thomas Blauwblomme, thomas.blauwblomme@aphp.fr
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