Dural cerebellopontine angle metastasis from malignant parotid oncocytoma.

Malignant oncocytoma of the parotid gland is a quite rare tumor, with only 40 cases with unequivocal histological diagnosis reported in the literature. No cases with intracranial metastasis have been described. The authors report a very unusual case of malignant parotid gland oncocytoma with a large dural extracerebellar metastasis occurring in the contiguous cerebellopontine angle six months after surgery for the primary tumor. Only a partial removal of the dural metastasis was possible because of the cranial nerve and vessel encasement within the mass. Surgery and irradiation resulted in one-year survival. Interestingly, no destruction and infiltration of the petrous and temporal bones were found both at radiological and surgical exploration. We may suggest that metastatic spread from the parotid region to the cerebellopontine angle occurred through the mastoid cells or by haematogenous diffusion through the meningeal branches to the posterior fossa dura from the occipital or ascending pharyngeal arteries.