title: MRI of mesenchymal chondrosarcoma of the orbit: case report and review of the literature.
abstract: Extraskeletal mesenchymal chondrosarcoma is a relatively uncommon entity, an orbital location being extremely rare. A review of the literature revealed 16 reported cases of primary orbital mesenchymal chondrosarcoma demonstrated by plain film and CT. To the best of our knowledge, the MRI features of orbital extraskeletal mesenchymal chondrosarcoma have not been previously reported. We present the case of an 18-year-old man with a 2-year history of progressive proptosis of the right eye who underwent CT, dynamic CT, MRI without and with gadolinium enhancement, and magnetic resonance angiography of the orbits. CT of orbital mesenchymal chondrosarcoma demonstrates a well-defined mass with multiple areas of fine and coarse calcification and shows moderate contrast enhancement. The noncalcified portions of the mass demonstrate signal intensity lower than or equal to gray matter on T1-weighted images and are isointense to the gray matter on T2-weighted images. Dynamic CT reveals delayed contrast enhancement. MRI has proven to be a valuable diagnostic tool in the diagnosis and differentiation of well-defined intraorbital masses. By a combination of CT and MRI, it appears mesenchymal chondrosarcoma can be differentiated from other intraorbital lesions, such as cavernous hemangioma, hemangiopericytoma, orbital amyloidosis and fibrous histiocytoma.
authors.affiliation: Department of Radiology, University of Illinois at Chicago Medical Center 60612, USA.
authors.forename: C N
authors.initials: CN
authors.lastname: Shinaver
authors.forename: M F
authors.initials: MF
authors.lastname: Mafee
authors.forename: K H
authors.initials: KH
authors.lastname: Choi
mesh_terms: D000293:Adolescent; D018211:Chondrosarcoma, Mesenchymal / Q000175:diagnosis*; D003937:Diagnosis, Differential; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009915:Orbit / Q000473:pathology; D009918:Orbital Neoplasms / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed