Metachronous Chondrosarcomas of the Paranasal Sinuses

Background: Chondrosarcomas most commonly develop in the pelvis, long bones or the ribs. Head and neck chondrosarcomas, account for only 1 to 12% of cases with those in the paranasal sinuses, being especially uncommon. Metachronous chondrosarcomas have been described outside the head and neck but this is the first report in the paranasal sinuses. Given the close proximity of vital structures adjacent to the sinuses, managing metachronous lesions in this location can be particularly challenging. Methods: We report the clinical presentation, radiographic findings, pathological examination, and combined surgical and oncological management of a patient presenting with metachronous chondrosarcomas of the paranasal sinuses. In this case, the patient developed three chondrosarcomas, distinct from one another in terms of both time and subsite, over a period of 15 years. We describe the management of complications from surgery and proton beam therapy; including the surgical decision making concerning operating on a new metachronous lesion affecting the orbit of the only seeing eye (vision having been lost on the contralateral eye following adjuvant proton beam therapy after excision of a previous sphenoidal chondrosarcoma). Discussion: We discuss the challenges of managing this complex and rare condition. We describe this in the context of what is known about metachronous chondrosarcomas in other sites.