Fetal type II lissencephaly: a case report.

Type II lissencephaly is a rare cortical malformation associated with a number of clinical syndromes, including Walker-Warburg syndrome and some forms of congenital muscular dystrophy. The neuropathology of a 20-week fetus is described showing the pathogenesis of the malformation, which appears to result from abnormal migration of neurons through the pial-glial barrier into the leptomeninges.