Histopathologic findings of malformations of cortical development in an epilepsy surgery cohort
E Brannon Morris1, Joseph E Parisi, Jeffrey R Buchhalter
1Divisions of Neurology and Neuro-Oncology, St. Jude Children's Research Hospital, Memphis, Tenn, USA.
Context:
Malformations of cortical development (MCDs) are an important cause of pharmacoresistent epilepsy and are frequently diagnosed in surgical pathology. The lack of uniform tissue processing and standard histopathologic nomenclature to describe MCDs has resulted in diagnostic ambiguity.
Objective:
To describe the immunohistochemical findings of MCDs from a relatively large surgical epilepsy cohort and incorporate terminology that more adequately reflects the histopathologic findings into a contemporary classification of MCD.
Design:
Utilizing the Mayo Clinic Rochester Surgical Pathology Database and patient records, 53 patients with previous intractable epilepsy and a known malformation of cortical development were identified. All of the cohort's paraffin embedded surgical specimens were resectioned and stained with hematoxylin-eosin, Luxol fast blue/cresyl violet, neurofilament protein, and glial fibrillary acidic protein. Each specimen was reviewed histologically and categorized according to a proposed focal MCD classification scheme that substitutes cytoarchitectural dysmorphism for cortical dysplasia and architectural disorganization for microdysgenesis.
Results:
An MCD was recognized in 49 patients and grouped into 1 of the following 4 categories: (1) cytoarchitectural dysmorphism with balloon cells (n = 19), (2) cytoarchitectural dysmorphism without balloon cells (n = 12), (3) architectural disorganization (n = 8), or (4) polymicrogyria (n = 9).
Conclusions:
The histopathologic features of focal MCD in a large epilepsy surgical cohort by using practical immunohistochemistry and a contemporary MCD classification scheme are described. It is proposed that the term focal cortical dysplasia be renamed as focal malformations of cortical development.
Insights
This study reclassifies malformations of cortical development (MCDs) in epilepsy surgery patients. A new classification system improves diagnostic clarity for these common causes of intractable epilepsy.
Area of Science:
- Neuropathology
- Epileptology
- Surgical Pathology
Background:
- Malformations of cortical development (MCDs) are a significant cause of drug-resistant epilepsy.
- Current diagnostic nomenclature for MCDs lacks uniformity, leading to ambiguity in surgical pathology.
- Standardized histopathologic descriptions are crucial for accurate MCD diagnosis.
Purpose of the Study:
- To detail immunohistochemical findings in MCDs within a large epilepsy surgery cohort.
- To propose a revised classification system for MCDs using contemporary terminology.
- To enhance diagnostic precision for malformations of cortical development.
Main Methods:
- Retrospective analysis of 53 patients with epilepsy and known MCDs from the Mayo Clinic Rochester Surgical Pathology Database.
- Histopathologic review of paraffin-embedded surgical specimens using H&E, Luxol fast blue/cresyl violet, neurofilament protein, and GFAP staining.
- Categorization of MCDs based on a proposed classification scheme, replacing 'cortical dysplasia' with 'cytoarchitectural dysmorphism' and 'microdysgenesis' with 'architectural disorganization'.
Main Results:
- Malformations of cortical development (MCDs) were identified in 49 patients.
- MCDs were classified into four groups: cytoarchitectural dysmorphism with balloon cells (n=19), without balloon cells (n=12), architectural disorganization (n=8), and polymicrogyria (n=9).
- The study provides a detailed histopathologic characterization of these MCD subtypes.
Conclusions:
- The study describes focal MCD histopathology in a large epilepsy cohort using practical immunohistochemistry and a contemporary classification.
- A revised classification scheme for malformations of cortical development is presented.
- It is proposed to rename 'focal cortical dysplasia' to 'focal malformations of cortical development' for improved clarity.
