Differentiation between osteoid osteoma and Brodie's abcess in a case of undiagnosed knee pain: radiological findings in a single case study

Osteoid osteoma is a benign skeletal neoplasm characterised by nocturnal pain that is relieved dramatically by salicylates. Brodie's abscess is the main differential diagnosis for osteoid osteoma, presenting with both clinical and radiological similarities. This report describes a 19-year-old female with a nine-year history of knee pain. Early investigations included plain radiographs, Magnetic Resonance Imaging (MRI) and arthroscopy, which were all identified as normal. The plain radiographs, MRI and Computed Tomography findings are discussed in relation to osteoid osteoma and Brodie's abscess and the need for diagnostic confirmation by biopsy.