A 10-year-old boy presents with fever, localized pain, and swelling in his mid-shaft of the tibia. X-rays show a permeative lesion with a characteristic 'onion-skin' periosteal reaction. What is the most likely diagnosis?

Explanation

Ewing's sarcoma is a highly malignant bone tumor that typically affects children and adolescents. It commonly presents with localized pain, swelling, and systemic symptoms like fever, mimicking osteomyelitis. Radiographically, it often appears as a permeative, destructive lesion in the diaphysis or metadiaphysis of long bones, with a characteristic 'onion-skin' (lamellated) periosteal reaction due to layers of new bone formation. Osteoid osteoma is a benign tumor with a small lucent nidus. Osteosarcoma typically presents with a 'sunburst' pattern and Codman's triangle in the metaphysis. Fibrous dysplasia has a 'ground-glass' appearance.