[A surgical case of ecchordosis physaliphora].

The authors report a rare case of ecchordosis physaliphora (EP) in the prepontine region. A 51-year-old woman was admitted with a small cystic mass in the prepontine region, complaining of headache and an episode of transient double vision. Plain X-ray and lateral tomography films showed a protrusive hyperostosis at the middle clival region. The CT scan showed no abnormal densities in the retroclival region, and CT cisternography showed an isolated small round mass in the prepontine cistern. A small cystic mass with no enhancement with Gd-DTPA was revealed on MRI, mildly compressing the basilar artery and the rostral surface of the pons. The totally excised mass was pedunculated and was contiguous with the dorsal wall of the clivus via a small dural defect. The histologic diagnosis was EP, consisting of scattered physaliphorous cell nests, which were not positive for MIB-1 staining. The pedicle consisted of mature cartilaginous cells. The authors briefly reviewed the few previously reported cases of symptomatic EP and intradural chordoma, and discussed the differences between them. The histological features, especially the proliferation potential, may be pathognomonic. The histogenesis and the clinical features of symptomatic EP are also provided.