Prenatal Imaging Findings of Pontine Tegmental Cap Dysplasia: Report of Four Cases.

ABSTRACT

OBJECTIVES: To describe the prenatal imaging findings in pontine tegmental cap dysplasia (PTCD), a rare congenital malformation of the hindbrain so far reported postnatally only and characterized by a typical appearance of the pons with malformations of the vermis and the cerebellar peduncles. METHODS: This retrospective multicenter study retrieved 4 cases of PTCD over a 10-year period. Prenatal ultrasonography and fetal magnetic resonance imaging (MRI) findings were reviewed and compared to postnatal or postmortem data. RESULTS: In all cases, the parents were referred between 22 and 27 weeks of gestation for characterization of a small cerebellar diameter <3rd centile. The prenatal diagnosis of PTCD was suspected in 1/4 cases, while in 3/4 cases the suggested prenatal diagnosis was pontocerebellar hypoplasia. In all cases, PTCD was characterized by ventral pontine hypoplasia with absence of bulging of the pons and by the tegmental cap protruding into the fourth ventricle on prenatal MRI. Parents opted for termination of pregnancy in 1 case. In the 3 other cases, the children presented with global developmental delay and multiple cranial nerve impairment. CONCLUSION: PTCD is a differential diagnosis of pontocerebellar hypoplasia and should be discussed on prenatal MRI in the presence of the tegmental cap protruding into the fourth ventricle.