Mesenchymal chondrosarcoma of the orbit: a report of two cases and review of the literature.

Mesenchymal chondrosarcoma, an uncommon lesion in bone and extraskeletal tissue, is extremely rare in the orbit. Two cases of orbital mesenchymal chondrosarcoma in young adults presenting with proptosis and diminution of vision are reported. The diagnosis was established by histopathological examination in both cases, which showed undifferentiated mesenchymal cells with islands of cartilage. Both patients underwent exenteration followed by chemotherapy and radiation therapy and are alive with healthy orbits after two years of follow-up.