MORPHOLOGICAL DIFFERENTIATION OF MARBLED STATE IN THE CEREBRAL CORTEX FROM POLYMICROGYRIA

Objectives: Polymicrogyria (PMG) is one of the common cerebral malformations, and accompanied with other brain disorders. Marbled state in the cerebral cortex (MSC) is occasionally observed in sequela of hypoxic ischemic encephalopathy (HIE), being related to the same change in the basal ganglia. Both entities have the similar neuropathological feature, and MSC can be misdiagnosed as PMG in small surgical specimens. Here we investigated morphological differences between PMG and MSC on immunohistochemistry and MRI.

Methods: Immunohistochemistry was performed in 6 cases each of PMG and MSC. PMG cases were not associated with porencephaly or metabolic errors, and MSC cases suffered from sequela of perinatal HIE or infantile encephalopathy/ meningitis. On immunohistochemistry, serial sections were treated with antibodies against glial markers including fibrillary acidic protein and myelin basic protein, calcium-binding proteins and glial glutamate transporters. MRI changes were evaluated in two cases each of PMG and MSC.

Results: On immunohistochemistry for glial markers, PMG cases showed two staining patterns, localized one in the molecular layer and diffuse one, whereas the perforating myelinated fibers with their circumference were stained in MSC cases. The expressions of calcium proteins were affected predominantly in PMG cases, while those of glial glutamate transporters were comparatively preserved in both PMG and MSC cases. On MRI, PMG cases demonstrated thickened cortex, altered cortical-white matter junction and thin perforating fibers from the white matter, whereas MSC cases showed thinned cortex and high T2 signals in the adjacent white matters.

Conclusion: Although it is difficult to differentiate MSC from PMG on routine histochemistry, two entities showed different immunohistochemical and MRI profiles. Recently, cortical dysgenesis has been reported in surgical specimens isolated from epileptic patients with HIE. We strongly recommend that the possible involvement of MSC should be considered in those patients.