Periosteal ganglion in a child.

A case of periosteal ganglion in a 10-year-old boy is reported. The diagnosis of periosteal ganglion was made on roentgenographic and MR appearance and histologic evidence. The patient was successfully treated by excision. The follow-up examination showed no recurrence. Periosteal ganglia must be considered a cause of expanding cortical erosions. This lesion may mimic other peripheral expanding lesions.