Diencephalic neuronal hamartoma associated with congenital obstructive hydrocephalus, anophthalmia, cleft lip and palate and severe mental retardation: a possible new syndrome

A male infant was born with severe hydrocephalus, bilateral cleft lip/palat e, left anophthalmos and right microphthalmos, and an equino-varus foot def ormity. Imaging studies showed enlarged lateral ventricles, apparent absenc e of the corpus callosum and a midline density in the third ventricular reg ion. He had a normal male karyotype. He was severely mentally retarded and died suddenly at 7 years of age. Neuropathological examination of the brain revealed enlarged and polygyric cerebral hemispheres, due to congenital ob structive hydrocephalus, and secondary thinning of the corpus callosum. An unusually large neuronal hamartoma filled the interpeduncular fossa and thi rd ventricle. It was continuous posteriorly with the left thalamus and so w as classified as diencephalic rather than as hypothalamic. The right optic nerve merged with the hamartoma, whereas the left nerve was absent. Microsc opically the hamartoma consisted of mature grey matter interspersed with na rrow bands of white matter. No immature or non-neural elements were identif ied. This combination of diencephalic neuronal hamartoma, hydrocephalus, oc ular and craniofacial abnormalities has not, to our knowledge, previously b een described.