A 10-year child presented with a mid tibial swelling which an x-ray revealed a lytic lesion with sclerotic margins. What is the most likely diagnosis?

An osteoid osteoma is a benign bone tumour that arises from osteoblasts and was originally thought to be a smaller version of an osteoblastoma. Osteoid osteomas tend to be less than 1.5 cm in size. A tumour can be in any bone in the body but are most common in long bones, such as the femur and tibia.