title: Orbital schwannoma with fluid-fluid levels on MRI.
abstract: A 40-year-old man presented with a progressively growing left orbital mass producing proptosis. Orbital MRI revealed a large bilobed mass that was isointense with respect to the extraocular muscles on T1-weighted images and demonstrated heterogenous contrast enhancement. T2-weighted images revealed a markedly heterogenous internal appearance with fluid-fluid levels. The mass was completely excised in one piece. Histopathologically, the encapsulated tumor consisted mostly of spindle-shaped tumor cells with elongated nuclei forming bundles without obvious mitosis. Richly cellular areas were consistent with the Antoni A pattern, and more hypocellular edematous areas were consistent with the Antoni B pattern. Hemorrhagic and cystic areas were seen within the tumor. The tumor cells stained diffusely positive with S-100 protein. Findings were consistent with the diagnosis of orbital schwannoma. Fluid-fluid levels are usually seen in some vascular and bone tumors and soft tissue lesions. Fluid-fluid levels have previously been reported to occur in intracranial but not in orbital schwannomas. This case demonstrates that orbital schwannoma can also display fluid-fluid levels on MRI, which were thought to be due to intralesional hemorrhage in this case.
authors.affiliation: Department of Ophthalmology, Ankara University Faculty of Medicine, Ankara, Turkey. eyemd@ada.net.tr
authors.forename: Kaan
authors.initials: K
authors.lastname: Gündüz
authors.forename: Rengin A
authors.initials: RA
authors.lastname: Kurt
authors.forename: Esra
authors.initials: E
authors.lastname: Erden
mesh_terms: D000328:Adult; D001826:Body Fluids; D003560:Cysts / Q000473:pathology; D005094:Exophthalmos / Q000175:diagnosis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009442:Neurilemmoma / Q000737:chemistry / Q000175:diagnosis* / Q000601:surgery; D009918:Orbital Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000601:surgery; D009418:S100 Proteins / Q000032:analysis
chemical_list: D009418:S100 Proteins