Mesenchymal chondrosarcoma of the orbit

Purpose: To describe a patient with mesenchymal chondrosarcoma of the orbit, review clinical and imaging findings, and refine the differential diagnosis from other tumors of the orbit. Methods: Interventional case report and literature review. Results: A 21-year-old woman with a 6-month history of progressive proptosis presented with left-sided visual loss of recent onset. CT revealed a clearly outlined heterogeneous mass with calcified foci, whereas MRI showed an isointense signal to gray matter on T-1- and T-2-weighted images. The patient was diagnosed with mesenchymal chondrosarcoma of the orbit only after orbitotomy and subsequent histopathologic study. After surgery, she received adjuvant therapy with irradiation of the orbit. Conclusions: Mesenchymal chondrosarcoma is a rare malignant tumor of the orbit capable of mimicking several other lesions. Early diagnosis requires a high level of suspicion, particularly with regard to internally calcified lesions. The treatment of choice is complete surgical resection, or, when the tumor is not resectable or residual mass is present after surgery, chemotherapy and radiotherapy. Prognosis for patients with orbital mesenchymal chondrosarcoma is tentative at best, in part because of the rarity of the lesion.