ABSTRACT

Osteoid osteoma is a benign bone tumour that causes significant nocturnal pain, cortical thickness and is relieved by salicylates. When it occurs, typical radiologic and clinical features are diagnostic. Radiography and computed tomography show a cortically based sclerotic lesion with a radiolucent nidus within it. The lesion usually involves long bones and most frequently presents in the diaphysis of the femur and tibia. Rare and unusually located lesions lead to misdiagnosis, even if the characteristic symptoms are present. We report an unusual case of osteoid osteoma in the tarsal navicular bone in which the diagnosis was delayed. This case, in which diagnosis was initially missed and treatment was delayed, resulted in a significant functional loss for the patient. A review of the literature revealed only two reported osteoid osteoma cases in the tarsal navicular bone.