High plasma-GFAP levels in metastatic myxopapillary ependymoma

Myxopapillary ependymoma (MPE) is a rare tumor of the distal spinal cord. Despite benign histopathology, local recurrences occur in ~30 % of patients and distant metastases have been described in few cases. MPE tumor cells typically express glial fibrillary acidic protein (GFAP), which could be released to the circulation. In this current report, we investigated circulating plasma-GFAP in a series of MPE patients. We analyzed circulating plasma-GFAP using a commercially available ELISA kit in 3 patients with completely resected MPE, 1 patient with locally advanced MPE and 2 patients with pleuropulmonary metastases of MPE. As controls we used blood samples of age and gender-matched healthy volunteers (n = 3), 6 glioblastoma patients with known plasma-GFAP status (positive for 3 and negative for 3 patients) and 3 brain metastases patients with known plasma-GFAP negativity. We found very high concentrations of plasma-GFAP in two MPE patients with pleuropulmonary metastases, while in none of the other MPE patients circulating plasma-GFAP was detectable. Circulating GFAP could be useful as marker for early detection or follow-up of distant metastases in MPE patients.