Temporal lobe focal cortical dysplasia: MRI imaging using FLAIR shows lesions consistent with neoplasia

Focal cortical dysplasia (FCD), a form of neuronal migration disorder, is a malformative lesion of the neocortex that occurs during development of the brain. It can cause partial and generalized epilepsy. Seizures occur at an early age and are often resistant to medication. Surgical resection has been found to be beneficial in these patients. Dual pathology, in the form of mesial temporal sclerosis, has been associated with FCD. At the Children's Hospital of Eastern Ontario, four patients with temporal lobe FCD have recently, been identified. This paper discusses how these children presented and how they were managed, with particular emphasis on their MRI findings and differential diagnoses. In three of the four patients neuroimaging studies showed lesions consistent with a neoplastic process because of the large volume and mass effect. Radiologically, FCD may mimic the MRI appearance of tumors, such as dysembryoplastic neuroepithelial tumors, primitive neuroectodermal tumors, gangliogliomas, oligodendrogliomas, and astrocytomas. These lesions are best visualized on fluid-attenuated inversion recovery (FLAIR) imaging, a technique that has recently become applicable in the clinical setting, as we help demonstrate in this series. With better MRI capability, milder forms of FCD and microdysplasia may be distinguished.