Spontaneous conversion of fibrous dysplasia into osteosarcoma.

Spontaneous degeneration of sarcomatosis of fibrous dysplasia is a rare phenomenon in adolescence. Fibrous dysplasia is often a deforming and devastating condition that begins in childhood and accounts for approximately 7.5% of the benign bone neoplasms. Approximately 50% to 100% of patients with polyostotic disease and 10% with monostotic disease have craniofacial involvement. This report is about a 16-year-old adolescent boy who had rapid facial mass growth and diplopia at the time of his referral to our center. The patient had been diagnosed with fibrous dysplasia a year earlier, and since the first diagnosis, he was submitted to only 1 surgical intervention, which had been followed by recurrence. The main clinical findings were a bilateral zygomatic mass, saddling of the nasal dorsum, diplopia, superior and inferior gaze, and numbness in the right inferior orbital nerve. The patient had a high level of serum alkaline phosphatase. The diagnosis of osteosarcoma was established by biopsy, and the patient underwent surgical treatment. His postsurgery results were good, and he did not experience a relapse until 1 year after surgery. Unfortunately, 6 months after the recurrence of his condition, he died of uncontrollable local spread.