Adult cerebellopontine angle choroid plexus papilloma: MR evaluation.

A 44-year-old man presented with a chief complaint of severe headaches of 3 weeks duration and left-sided unsteadiness. Cranial CT showed a well-marginated, oval, homogeneously enhancing mass within the left CPA cistern. The lateral ventricles appeared moderately dilated. MR study (Fig. 1) showed a parenchymal isointense mass within the left CPA producing upward displacement of the left middle cerebellar peduncle. The tumor appeared to extend from the lateral recess of the fourth ventricle into the CPA via the foramen of Luschka. Extension through a ventricular outlet has recently been emphasized as a characteristic of choroid plexus papillomas (1). The associated hydrocephalus, especially the dilatation of the anterior third ventricle, also was well delineated by the MR examination (2). At surgery a red, friable solid lesion 1.0 x 0.5 x 0.5 cm with cystic components resembling a cauliflower was removed from the CPA and left cerebellar hemisphere. Microscopic examination showed papillae composed of a single layer of columnar epithelium supported by a stroma of vascularized connective tissue. The specimen was devoid of fibrillary neuroglia, a finding that distinguished the specimen from ependymoma (3). Pathologic evaluation was consistent with choroid plexus papilloma.