Osteoid osteoma of the distal radius presenting as an inconspicuous swelling in a young child

Osteoid osteoma is a benign osteoblastic tumour with a predilection for the lower extremity that rarely affects the forearm. It is commonly seen in adolescents and young adults, and is seldom diagnosed in the paediatric age group. We report a boy in his early childhood who presented with a swelling over the distal forearm, which was incidentally noted by the mother 3 months ago. Plain radiographs showed diffuse sclerosis of the dorsal cortex of the distal radius. CT scan showed a central lucent nidus in the intramedullary region and surrounding sclerosis in the radial metaphysis, confirming the diagnosis of osteoid osteoma. The patient was successfully treated by surgical en bloc resection of the nidus and was asymptomatic at 1-year follow-up. Non-specific symptoms at presentation make it a challenge to diagnose osteoid osteoma in children and it needs to be considered in the differential diagnosis when radiographs show lytic lesions in the bone.