Meningeal solitary fibrous tumor as an unusual cause of exophthalmos: Casereport and review of the literature

OBJECTIVE AND IMPORTANCE: We report an extremely rare case of a patient wit h meningeal solitary fibrous tumor with orbital involvement presenting as u nilateral exophthalmos. This rare tumor should be considered in the differe ntial diagnosis for aggressive dural-based lesions. CLINICAL PRESENTATION: A 54-year-old man presented with a protruded eyeball on the right side and left hemiparesis. Computed tomography and magnetic r esonance imaging demonstrated a huge mass, markedly enhanced in and around the right anterior clinoid process, which extended to the orbit and middle cranial fossa. Cerebral angiography revealed a richly vascular tumor fed by branches of both the right external and internal carotid arteries. A presu mptive diagnosis of meningioma or hemangiopericytoma was considered. INTERVENTION: The tumor was exposed through an orbitozygomatic approach. At surgery, the tumor was grossly firm to hard and had destroyed the dura, or bital roof, anterior clinoid process, temporal bone, and muscle. Histologic al analysis revealed that the tumor was composed of spindle-cell proliferat ion in a collagen-rich background, but it exhibited regional variations. Th e vascular network demonstrated irregular vascular lumina with a "hemangiop ericytoma-like" pattern. Histological features included high cellularity an d a high degree of pleomorphism. Immunohistochemical analysis of the tumor demonstrated diffuse positive staining for CD34 and vimentin. The tumor dis played no positive staining for cytokeratin, epithelial membrane antigen, g lial fibrillary antigenic protein, S-100 protein, and factor XIII. CONCLUSION: Meningeal solitary fibrous tumor is considered a unique patholo gical entity. Wider use of immunohistochemical screening should enable anal ysis of the real incidence of these tumors; larger series and longer follow -up duration will allow conclusions to be drawn regarding treatment and pro gnosis. Differential diagnosis is discussed and the literature is reviewed.