Transmantle Focal Cortical Dysplasia: A Clinicopathologic Study of 12 Cases Emphasizing Histopathologic Features
Michael J Cascio, Doris D Wang, Abby E Deans, A James Barkovich, Tarik Tihan. UCSF, San Francisco
Background: Cortical dysplasias are a heterogeneous group of disorders that often result in pharmaco-resistant epilepsies. In epileptic patients, the incidence of focal cortical dysplasia ranges from 12-40%. Focal cortical dysplasia can be classified by pathologic and radiologic characteristics. Transmantle focal cortical dysplasia (TFCD) is a subset of focal cortical dysplasia that is defined by its distinctive neuroradiologic appearance. To date, the microscopic features of this entity have not been well characterized. In this study, we describe the detailed histopathologic features of TFCD and compare the findings with those of other focal cortical dysplasias.
Design: All cases of focal cortical dysplasia diagnosed and treated at our institution were reviewed and those that fulfilled the radiological criteria for TFCD were included in the study. An age and gender-matched control group was selected among patients with focal cortical dysplasia without radiologic criteria for TFCD. ILAE Type III cases were excluded. For each case, patient age, gender, site of lesion, clinical presentation and outcome were recorded. Histopathologic features were compared between the two groups.
Results: There were 12 patients with radiological features that fulfilled the criteria for TFCD. The group included 6 males and 6 females with a median age of 16.5 years (range, 7 months to 24 years). The lesions were identified in the parietal (17%), frontal (59%), temporal lobe (8%), and occipital lobes (8%). In one patient, the lesion was holohemispheric. Complex partial seizures were the most common presenting seizure type, with two patients demonstrating generalized tonic-clonic seizures. Gross total resection was achieved in 11 cases. Histological evaluation demonstrated dysmorphic neurons in 75%, disruption of the cortical lamination in 75%, hypercellularity in 50%, reactive gliosis in 17%, heterotopic foci in 17%, neuronal cytomegaly in 25% and balloon cells in 50%. In almost all cases there were an increased number of bizarre neurons within the deep white matter included in the resections.
Conclusions: The cardinal histological features of TFCD seem to be indistinguishable from typical focal cortical dysplasia. TFCD appeared to be more commonly associated with the presence of bizarre neurons in the deep white matter, but larger studies are needed to substantiate this impression. We conclude that TFCD is best distinguished from other types of cortical dysplasia by its distinctive neuroradiologic appearance.
Tuesday, March 20, 2012 1:00 PM
Poster Session IV # 276, Tuesday Afternoon