Medulloblastoma is a common malignant central nervous system neoplasm found mainly in children. One the contrary, medulloblastoma of the cerebellopontine angle, the location of the tumor is very unusual. This is the the first case of the medullomyoblastoma, a rare form of medulloblastoma, occurring in the cerebellopontine angle. A 15-year-old boy experienced a sudden hearing loss in the left ear. Conservative medical treatment failed, and temporal MR imaging revealed a heterogeneously enhancing mass at the left cerebellopontine angle cistern and in the internal auditory canal; therefore, the lesion was regarded as a typical acoustic neuroma. Few days before surgery, an ipsilateral facial palsy developed, and a follow-up MR imaging showed a rapid growth of the previous lesion. The extended translabyrinthine approach permitted surgical removal. And under pathological diagnosis of malignancy, radiation therapy and series of chemotherapy was performed.