A rare costal tumor complicating a solitary osteochondroma

Introduction: Chondrosarcoma complicating osteochondromatous lesions is a microscopic diagnosis which treatment is based on surgical excision. These tumors need a close followup because the recovery can be ascertained only after 10 years of follow-up. Case Report: A 19-year-old male who presented respiratory symptoms and whose past medical history was remarkable for a previously noted cartilaginous exostosis in multiple long bones. Physical and radiologic investigations showed a mass attached to the first rib. The anterior arch of the rib was excised en-bloc with a layer of soft tissue. Histopathological examination concluded to a grade I chondrosarcoma arising from an osteochondroma. Conclusion: Secondary chondrosarcoma complicating a benign lesion such as osteochondroma has been rarely reported in the rib. We aim to highlight the diagnostic and therapeutic challenges of this rare tumor by describing a new case of secondary costal chondrosarcoma.