Primary choroid plexus papilloma of the sacral nerve roots.

The authors describe a unique case of a choroid plexus papilloma of the sacral nerve roots. This 60-year-old woman was admitted to the hospital because of a 1-year history of sacral pain, rectal and urinary bladder retention, and paradoxical episodic incontinence. Physical examination revealed sensory abnormalities in the S-2 dermatomes and poor rectal and bladder sphincter contractions. Contrast-enhanced spinal MR imaging showed a well-circumscribed, ovoid, homogeneously enhancing mass at the S1-2 level suggesting a diagnosis of ependymoma or schwannoma, and surgery allowed the identification and complete removal of a soft gray mass intimately adhering to the sacral nerve roots. Histological examination revealed a tumor consisting of papillary structures lined by a single layer of columnar cells, with an immunophenotype that satisfied the diagnostic criteria of choroid plexus papilloma. After diagnosis, contrast-enhanced brain MR imaging excluded the presence of a primary choroid plexus papilloma in the cerebral ventricles, thus ruling out a drop metastasis along the CSF pathways. A review of the literature did not reveal any similar cases of choroid plexus papilloma, and so the authors also discuss the inclusion of primary or metastatic papillary tumors in this unusual location as part of the differential diagnosis.