Mesenchymal chondrosarcoma, an uncommon lesion of bone and extraskelet
al tissue, is rare in the orbit. A case of extraskeletal mesenchymal c
hondrosarcoma of the orbit in a 28-year-old woman presenting with prop
tosis and diminution of vision in the left eye is reported. Histologic
ally, the tumor showed areas of undifferentiated mesenchymal cells wit
h islands of cartilage. Immunohistochemical analysis for S-100 protein
showed focal positivity in chondroid areas. The eye was preserved and
the patient has good vision after 2 years of follow-up.