A 14-year-old female presents with a 4-month history of persistent pain and swelling in her right proximal tibia. The pain is worse at night and unrelieved by rest. On physical examination, a firm, tender mass is palpable over the proximal tibia. An X-ray reveals a destructive lesion with a “sunburst” periosteal reaction and a Codman triangle. Biopsy confirms high-grade osteosarcoma. Which of the following syndromes is most commonly associated with an increased risk of developing this condition?
