CNS nontumor

• Focal cortical dysplasia (FCD) represents a phenotypically diverse group of developmental disorders marked by abnormalities of cortical architecture

• Focal cortical dysplasia is marked by cortical architectural abnormalities secondary to disruptions of cortical development
• Most patients clinically present with epilepsy and in a subset of pharmacoresistent cases, surgery may be employed in an attempt to control the seizures
• Some focal cortical dysplasia patterns may be grossly evident (e.g., polymicrogyria, pachygyria, heterotopia)
• The most common morphologic patterns encountered include disruptions in the cortical architecture in either a horizontal or vertical orientation; a subset of cases may demonstrate dysmorphic cortical neurons or balloon cells
• Focal cortical dysplasia may arise in association with other pathologies, most notably hippocampal sclerosis and tumors (gangliogliomas, dysembryoplastic neuroepithelial tumors)

• Malformations of cortical development, microdysgenesis

• ICD-10: Q04.8 - other specified congenital malformations of brain

• Any of the cortical lobes may be affected (frontal and temporal most common)

• EEG and imaging studies (high resolution MRI) studies may be useful in localizing seizures
• Pathologic examination of excised tissues to confirm the diagnosis

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Images hosted on other servers:

• Frozen sections not typically used, unless there is a coexistent lesion (e.g., tumor) that is also being excised

Contributed by Richard Prayson, M.D.

• Neurology 2004;62:S2, J Neuropathol Exp Neurol 1995;54:137, Neurosurgery 1988;23:545, J Neuropathol Exp Neurol 1995;54:513, Epileptic Disord 2019;21:122

A 6 year old female patient presents with a history of temporal lobe epilepsy since age 3 years. A variety of pharmacologic treatment regimens have been attempted to control the seizures with varying temporary success. On imaging, she has an area of vague enhancement in the right temporal lobe. Concerned about a possible tumor, the area of enhancement is excised. The pathology is shown here. What is the best diagnosis for the lesion seen here?

1. Dysembryoplastic neuroepithelial tumor
2. Focal cortical dysplasia ILAE type I
3. Focal cortical dysplasia ILAE type II
4. Ganglioglioma
5. Pleomorphic xanthoastrocytoma

C. Focal cortical dysplasia ILAE type II. The lesion is marked by the presence of dysmorphic neurons and occasional balloon cells, characteristic of focal cortical dysplasia IIB. Focal cortical dysplasia type I does not contain dysmorphic neurons or balloon cells. Dysembryoplastic neuroepithelial tumors are low grade glioneuronal neoplasms marked by multinodularity and a mixture of rounded oligodendroglial-like cells intermixed with normal appearing neuronal cells, often arranged against a microcytic background. Gangliogliomas have an atypical glial cell component along with dysmorphic ganglion cells. Pleomorphic xanthoastrocytomas are characterized by prominent cellularity with an atypical astrocytic component and variable numbers of xanthoastrocytes.

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Reference: Focal cortical dysplasia (epilepsy related malformations)

Which of the following tumors is most likely to be associated with coexistent focal cortical dysplasia?

1. Fibrillary astrocytoma
2. Ganglioglioma
3. Meningioma
4. Oligodendroglioma
5. Pilocytic astrocytoma

B. Ganglioglioma. Tumors known to be associated with coexistent focal cortical dysplasia include ganglioglioma, dysembryoplastic neuroepithelial tumor, angiocentric glioma and rare cases of pleomorphic xanthoastrocytoma. The other tumors listed as options with the question are not known to be associated with focal cortical dysplasia.

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Reference: Focal cortical dysplasia (epilepsy related malformations)