Worsening left ankle pain

A 15-year-old boy reported to the clinic with increasingly worsening left ankle pain since he began football practice. An x-ray (Figure 1) revealed a multilocular lucent lesion spanning 5.9 cm by 3.7 cm by 4.8 cm with well-circumscribed edges expanding the anterior cortex near the distal anterior metaphysis of the left tibia. The diagnosis was verified by magnetic resonance imaging (MRI).