[Adult choroid plexus papilloma of the posterior fossa: extraventricular location].

Choroid plexus papillomas (CPPs) are rare neuroectodermal neoplasms accounting for 0.4% of all intracranial neoplasms in adults. Most of them are located in the posterior fossa in adults. Although CPPs commonly arise from the 4th ventricle, they occasionally extend to extraventricular space. Furthermore some occur primarily in the extraventricular region. It is difficult to diagnose CPP preoperatively when the main portion of the tumor is not located in the 4th ventricle. We present a case of a 54-year-old male manifesting slurred speech, nystagmus and cerebellar ataxia. Magnetic resonance imaging demonstrated an intracerebellar solid tumor with multilocular cysts, extending towards both the right lateral medullary region and the foramen of Luschka. Computed tomography scans showed patchy calcification at the periphery of the solid component. Angiographically, via the right posterior inferior cerebellar artery revealed the tumor was faintly opacified. Preoperative diagnosis included meningiomas, low-grade astrocytomas, ependymomas or CPPs, but none of them had neuroradiologically decisive findings. Tumor was subtotally resected through a right suboccipital craniectomy. A calcified solid portion adhering to the lower cranial nerves was left unresected. The pathological finding was CPP. CPP should be considered among calcified and enhanced masses in the lateral medullary to cerebellopontine angle space in adults, even if the main portion of the tumor is not located in the 4th ventricle.