A 4-year-old girl with PHACES syndrome (posterior fossa brain malformations, hemangiomas, arterial anomalies, cardiac anomalies/coarctation of the aorta, eye abnormalities, and sternal clefting/supraumbilical raphe) developed a cerebellar pilocytic astrocytoma 18 months after resolution of her neck, ear, and thoracic hemangiomas. Because cutaneous hemangiomas may have involuted by the time a patient is diagnosed with a central nervous system neoplasm, it seems possible that in other such patients the association may have gone unrecognized. Cerebellar pilocytic astrocytoma may be a rare manifestation of the posterior fossa malformations of PHACES.