Rhabdoneuroglial heterotopias of the pontine leptomeninges in trisomy 13.

An unusual heterotopia of striated skeletal muscle and glial tissue occurred in the pontine meninges of a stillborn male showing feature of trisomy 13 and an Arnold-Chiari malformation. In two other reports of this type of heterotopia, the location and association with trisomy 13 has been the same. An error in tissue differentiation at the pontine flexure is suggested to account for this relationship.