Lissencephaly Microlissencephaly This is a severe phenotype that can be diagnosed at the fetopathological level, by which a diagnosis of lissencephaly can be made by the examination of the 6 layers of the cortex. Examination may show 3 layers or an extremely thin cortical plate consistent with the diagnosis of lissencephaly. Severe microcephaly and lissencephaly with granular surfaces with immature cortical plate, reduced in thickness, with focal polymicrogyria and immature small neurons with rare processes, intermingled with a considerable number of glial elements. Type III lissencephaly Lissencephaly type III UMLS:C4021030 Type 3 lissencephaly