Epileptologists from the Case Medical Center, Cleveland, Ohio; and the Comprehensive Epilepsy Center, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, are guest editors of the December 2013 Epilepsia Supplement on Tumors and Tumoral Epilepsy. Among 24 items discussed, one deals with the relation of developmental brain tumors to adjacent cortical dysplasia. The natural histories and presentations of "epileptomas" and "long-term epilepsy-associated tumors (LEATS)" differ according to histologic subtype. The associated pathologies of focal cortical dysplasia (FCD) and developmental tumor raise the question of epileptogenicity of FCD and the necessity to resect both tumor and adjacent dysplasia. Is the tumor and dysplasia the same lesion with distinct components along a developmental continuum, or is the FCD an entirely separate lesion, not requiring surgical resection? If the tumor and surrounding dyslaminated tissue are considered epileptogenic lesions on their own, or dual pathologies, surgical resection of both is indicated. If both are part of the same histopathologic continuum, or if the surrounding dyslaminated cortex is an incidental finding, the surgical relevance of the dysplasia as epileptogenic tissue is variable. Seizure control may be achieved by partial resection of only the epileptogenic zones of the lesion. Acute electrocorticography (ECoG) shows two patterns: 1) frequent, almost continuous spiking, found over the tumor and its immediate surroundings, areas requiring complete resection, and 2) occasional, intermittent spikes, over areas usually non-epileptogenic and not requiring resection. [1, 2]
COMMENTARY. Association of FCD with dysembryoplastic neuroepithelial tumor (DNT). DNT is a glioneuronal tumor, increasingly recognized as a cause of intractable partial epilepsy in children. Located in the supratentorial cortex, especially the temporal lobe, DNT occurs in three histologic subtypes (simple, complex, and nonspecific). Complex and nonspecific forms are frequently associated with FCD. Based on a series of 78 patients, aged 3-54 years, seen at Sainte-Anne Hospital and other centers in Paris, France, 73% of DNTs were located in the temporal lobe. Histologic subtypes differentiated by MRI were Type 1 (cystic/polycystic-like, complex or simple forms), and Type 2 (nodular-like) and Type 3 (dysplastic-like) nonspecific forms. The epileptogenic zone varied according to MRI subtype: surgical resection could be restricted to the tumor in type 1 and was more extensive in other MRI subtypes, especially in type 3 MRI. Early surgical excision is important in control of DNT-associated epilepsy .