Byun H: Agenesis of bilateral internal carotid arteries and posterior fossa abnormality in a patient with facial capillary hemangioma: Presumed incomplete phenotypic expression of PHACE Syndrome

drome with the following features: posterior fossa malfor-mations of the brain, large facial hemangiomas, arterial anomalies, cardiac anomalies and aortic coarctation, and eye abnormalities. We report a rare case of bilateral inter-nal carotid artery agenesis with transcranial collaterals from the external carotid arteries and agenesis of the ver-tebrobasilar system in a possible PHACE syndrome. We suggest that the patient had an incomplete phenotypic expression of the PHACE syndrome. Although the pheno-typic spectrum is broad and is still largely unexplored, the extent of the cephalic neural crest cells insulted genetically or by other causes at a certain time during the development of the embryo might explain the variable phenotypic ex-pression of PHACE syndrome. Agenesis, aplasia, and hypoplasia of the interna