Tuberous sclerosis complex with a single brain lesion on MRI mimicking focal cortical dysplasia

Of 105 children with epilepsy who had presurgical evaluation because of solitary extratemporal focal cortical dysplasia, the 5 cases reported here had a final diagnosis of tuberous sclerosis complex without classic findings on magnetic resonance imaging (MRI). Four were infants with spasms (n = 2) or partial seizures (n = 2); the fifth was a 12-year-old boy with right motor seizures. Cranial MRI indicated solitary left frontal dysplasia in two cases (one with calcification) and right frontal, left parietal, and right parietal dysplasia in one case each. Tuberous sclerosis complex was considered based on hypopigmented macules in three cases, on cardiac rhabdomyomas on echocardiography for hypotension in one case, and on calcification in the dysplastic region and a family history of seizures in one case. Four of the patients had mutations in the TSC1 (n = 2) and TSC2 (n = 2) genes. No mutation was found in the fifth patient, who had only TSC1 sequencing. Four had epilepsy surgery, and were seizure-free on one (three cases) or two antiepileptic drugs (one case) at 1-2 year follow-up. Pathologic examination revealed cortical dysplasia without any characteristic features of tuberous sclerosis complex. These findings suggest that, in tuberous sclerosis complex, solitary focal cortical dysplasia may be the only cranial MRI finding. Tuberous sclerosis complex should be considered when focal cortical dysplasia is associated with seizure onset in infancy, family history of seizures, and peridysplastic calcification.