29th April 2024

A 12-year-old boy presents with a 3-week history of progressive pain in his left lower leg.

A 12-year-old boy presents with a 3-week history of progressive pain in his left lower leg. The pain is constant and worsens at night. He has a low-grade fever and has been limping for the past week. He had a minor scrape on his leg 1 month ago. On examination, the leg is swollen and tender over the tibia, and there is local warmth and redness.

Investigations:

White cell count: Elevated

C-reactive protein (CRP): Elevated

Erythrocyte sedimentation rate (ESR): Elevated

X-ray of the leg: Periosteal reaction and cortical irregularities in the tibia

MRI of the leg: Bone marrow edema in the tibia

Which is the most likely diagnosis?