Secondary osteosarcoma is a rare complication of primary malignancies and benign bone lesions. There are various types of diseases that cause secondary osteosarcoma. A 15-year-old male presented at our medical center complaining of pain and redness in the right lower leg. He had been diagnosed with osteofibrous dysplasia in the right tibia when he was 2 years old and since then had been followed up. Although he had a pathological fracture of the right tibia at the age of 7, his fracture healed with a plaster cast and did not require surgery. At the time of the patient’s last visit, a radiograph revealed a periosteal reaction as well as erosion of the bone cortex. Magnetic resonance imaging revealed an infiltrative area in the soft tissue surrounding the osteofibrous dysplasia lesion in the tibia. Consequent to pathological examination (through bone biopsy), the patient was diagnosed with secondary osteosarcoma. The patient underwent chemotherapy and extensive resection with liquid nitrogen. He has been progressing satisfactorily after the operation. The present case is the first report of secondary osteosarcoma associated with osteofibrous dysplasia. During the long-term follow-up of osteofibrous dysplasia, oncologists should be aware of the possibility of secondary osteosarcoma.

继发性骨肉瘤是原发性恶性肿瘤和良性骨病变的罕见并发症。引起继发性骨肉瘤的疾病种类繁多。一名 15 岁男性因右小腿疼痛和发红到我们医疗中心就诊。他在 2 岁时被诊断出患有右胫骨骨纤维发育不良，此后一直进行随访。虽然他在 7 岁时右胫骨发生病理性骨折，但他的骨折通过石膏固定愈合，不需要手术。在患者最后一次就诊时，X 光片显示骨膜反应以及骨皮质侵蚀。磁共振成像显示胫骨骨纤维异常增生病变周围的软组织有浸润区。病理检查（通过骨活检）后，患者被诊断为继发性骨肉瘤。患者接受了化疗和广泛的液氮切除术。手术后，他的进展令人满意。本病例是首例与骨纤维异常增生相关的继发性骨肉瘤的报道。在骨纤维异常增生的长期随访过程中，肿瘤学家应该意识到继发性骨肉瘤的可能性。