Summary

Extraskeletal orbital mesenchymal chondrosarcoma (MC) is an extremely rare and highly aggressive tumour. It has characteristic radiological features and pathognomic histological biphasic pattern. Radical resection with negative margins is the mainstay of treatment; role of adjuvant chemotherapy and radiotherapy is yet not well defined. We report a rare case of 18-year-old man who was diagnosed to have orbital MC. He presented with locally advanced disease with no vision in the affected eye. He underwent right orbital exenteration; a transcranial intradural approach was used to divide the optic nerve, and the temporalis muscle flap was utilised to fill the exenterated orbit. Though optic nerve involvement is rare in orbital MCs, a transcranial approach may be used effectively to avoid traction on optic chiasma and ensure margin-free resection in case of optic nerve involvement up to orbital apex. Unfortunately, prognosis remains dismal in MCs despite treatment.