[Metaplastic ossification in an acoustic neurinoma].

We report the case of a 52-year-old woman with a cerebellopontine angle tumor, which appeared to have arisen from the 8th nerve. Microscopically the tumor was proved to be an acoustic neurinoma and showed unusual findings such as inclusions of mature bone and bone marrow. The histogenesis and diagnostic relevance of the very rare heterotopic osteogenesis in acoustic neurinomas is discussed.