Focal cortical dysplasia type III Focal cortical dysplasia type IIIa 2018-09-16T11:16:43Z A subtype of focal cortical dysplasia type III that is characterized by alterations in architectural organization (cortical dyslamination) or cytoarchitectural composition (hypertrophic neurons outside Layer 5) in patients with hippocampal sclerosis (also known as Ammon's horn sclerosis).