Intracranial Fibro-Osseous Lesion: A case report and literature review

Lim, Jae Weon; Lee, Seung Cheol; Yi, Byoung Yuk; Sohn, Yoon Kyung

Abstract

Intracranial fibro-osseous lesion, also reported as calcifying pseudoneoplasm of the neural axis, is an uncommon lesion of the central nervous system. Since the discovery of this entity by Rhodes and Davis in 1978, there have been a total of 21 cases reported in the literature. We encountered one such case in a 28 year old male, who presented with left hemiparesis for 1 year. By the MR images, a 1.5 cm sized round mass was found at right parietal lobe near motor cortex. The mass lesion enhanced well, homogenously and revealed clear, slightly irregular margin. Excisional biopsy of the mass was performed. Microscopically the lesion was composed of calcified fibrous tissue with an amorphous gray-blue, coarsely fibrillar to chondromyxoid nodular areas. Sparse spindle cells, immunohistochemically negative for GFAP, vimentin and S-100, were scattered within the amorphous material. Palisading spindle or polygonal cells were present at the more cellular periphery of the lesion, which were vimentin positive but S-100 negative. There was no evidence of the pilocytic astrocytes, Rosenthal fibers, or GFAP positive hypertrophic astrocytes. Intracranial fibro-osseous lesions are apparently slow-growing with generally excellent prognosis after wide excision. The etiology remains unclear, but most investigators favor a reactive rather than neoplastic process.