Mixed tumour of schwannoma and meningioma components in a patient with NF-2.

The authors present the case of an intracranial tumour consisting of both schwannoma and meningioma within the same tumour, in a patient with neurofibromatosis-2 (NF-2). A pre-operative diagnosis of this mixed tumour was not made. However, retrospectively, a meningiomatous area was found inside the acoustic neurinoma on magnetic resonance (MR) images. Predominant schwannoma with a minor component of meningioma was confirmed by histopathological and immunohistochemical examinations. The transitional zones of these two different tumours were macroscopically sharp but microscopically interdigitated. The patient had another meningioma and schwannoma in a separate section of the cranial cavity. Based on this patient, it is suggested that the collision of two kinds of tumours is the most likely hypothesis to explain the development of mixed components of schwannoma and meningioma within the same tumour.