Focal cortical dysplasia - type IIB
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A region of high T2 signal associated with lower than expected T1 signal and blurring of the grey white matter junction is seen in the inferior precuneus on the left.
The patient went on to have a craniotomy and resection.
Sections show multiple fragments of cortical tissue with underlying white matter. In most of the oriented tissue fragments, the laminar arrangement of neurons is appreciated. However, in some other cortical tissue fragments there is a random and haphazard arrangement of neurons with loss of the normal laminar architecture. Subpial gliosis strongly positive for GFAP is noted in these abnormal cortical areas, which also contain abnormally placed scattered neurons in the subpial region. Some of the glial cells in the outer cortex contain intracytoplasmic granular brown pigment. There are scattered minute, multifocal aggregates of randomly oriented neurons, oligo-like cells and astrocytes consistent with microdysgenetic foci. There are occasional areas in which disoriented neurons and glial cells are associated with prominent vessels vaguely resembling dysembryoplastic neuroepidermal tumor (DNT), but do not have all the features of DNT. Occasional ballooned neurons and abnormal forms and sometimes binucleate neurons are seen. In addition, in the white matter, scattered neurons are identified. The Bielschowsly stain and chromogranin immunostaining highlight some of the abnormal neurons.
Focal cortical dysplasia and microdysgenesis.