The authors present the case of an intracranial tumour consisting of b
oth schwannoma and meningioma within the same tumour, in a patient wit
h neurofibromatosis-2 (NF-2). A pre-operative diagnosis of this mixed
tumour was not made. However, retrospectively, a meningiomatous area w
as found inside the acoustic neurinoma on magnetic resonance (MR) imag
es. Predominant schwannoma with a minor component of meningioma was co
nfirmed by histopathological and immunohistochemical examinations. The
transitional zones of these two different rumours were macroscopicall
y sharp but microscopically interdigitated. The patient had another me
ningioma and schwannoma in a separate section of the cranial cavity. B
ased 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.