Unusual case of extradural choroid plexus papilloma of the sacral canal. Case report.

An unusual case of a sacral, extradural choroid plexus papilloma involving the S1-3 level is described. This 50-year-old woman presented with a 4-month history of pain involving her right buttock, perineum, and leg. Contrast-enhanced magnetic resonance (MR) imaging of the spine revealed a well-defined, mildly enhancing sacral canal mass at the S1-3 level; its appearance was consistent with that of a benign tumor. Intraoperatively, the lesion was found to be extradural in location and was entwined among nerve roots in the sacral canal. Microscopic examination of the gross totally resected tumor revealed typical features of a choroid plexus papilloma. Despite performing a thorough neuroimaging workup (craniospinal contrast-enhanced MR imaging) for an intracranial or spinal primary mass, none was found. The choroid plexus appeared entirely normal; however, both a cavum septum pellucidum and a cavum vergae were noted. Extraneural choroid plexus papilloma, specifically intrasacral, extradural choroid plexus papilloma has not been previously reported. The present example is thought to have arisen either from ectopic choroid plexus tissue or perhaps by metaplasia from ependymal rests.