Paraganglioma of the filum terminale.

An unusual tumor arising in the filum terminale is described. The clinical data revealed an extensive and slowly growing lesion. The histologic picture was characterized by a proliferation of lobules and sheets of regular cells within a rich vascular network. Electron microscopic studies showed light and dark cells with sustentacular extensions. Typical neurosecretory granules were observed in both cell types, establishing the diagnosis of para-ganglioma. The glomus coccygeum could be the site of this tumor.