Metastasis of a histologically benign choroid plexus papilloma: case report and review of the literature.

Cerebrospinal metastases of benign choroid plexus papillomas (CPPs) are extremely rare. We report a case of 32-year-old woman who presented with a 6-month history of vertigo and intermittent headache. Plain CT scan of the cranium revealed a partly calcified tumor filling the fourth ventricle and its right recess. Cranial MRI showed an inhomogeneously contrast-enhancing tumor and leptomeningeal enhancement encasing the brain stem. Complete resection of the tumor was carried out, and seedings to the floor of the fourth ventricle and cervico-medullary junction were found during the operation. While intraoperative frozen section suggested pathology of papillary ependymoma or CPP, to our surprise, final histological examination revealed a benign choroid plexus papilloma. One month after the first operation, a metastatic nodule was found in the spinal subarachnoidal space at the level of T8-9. Two months after the first operation, on follow-up MRI of the cranium, the leptomeningeal enhancement encasing the brain stem had resolved spontaneously. This special case helps increase our understanding of benign CPPs and expands our differential diagnostic consideration of lesions with similar manifestations.