[A case of primary orbital chondrosarcoma].

The case of a twenty-year-old male with orbital chondrosarcoma is reported. He visited National Defense Medical College Hospital because of reduced vision in the right eye since two months previously. His corrected visual acuity was 8/20 in the right eye and 20/20 in the left eye. Fifteen degrees lateral displacement of the right globe and limitation of right ocular movement were recognized. Right fundus examination revealed optic disc edema and protuberant nasal fundus. Orbital computed tomography (CT) demonstrated a high density area between the inner part of the right orbit and the ethmoid sinus. Magnetic resonance imaging (MRI) showed a smoothly outlined and low intensity (T1) space occupying lesion. This lesion was irregularly enhanced by gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA). This orbital tumor was removed by an anterior approach. Histopathological examination revealed well-differentiated chondrosarcoma (grade 1) as determined by small prominent chondromatous cell projection into the collagen fibrous stroma, and existence of binucleate cells in the hypercellular region. After the operation the disc edema disappeared and his corrected right visual acuity improved to 20/20.