What is the differential diagnosis for such a lesion?
Chronic osteomyelitis should always be in the differential when thinking of osteoid osteoma.
CT roughly 9 mth after initial XR
CT confirms an approximately 5 mm lytic nidus with central punctate calcification surrounded by sclerotic trabecular, cortical and periosteal reaction. 3D reconstructions depict the undulated, smooth periosteal thickening.
Incidentally, posteromedially to this lesion, there is a sclerotic focus of bone most likely representing an enostosis (bone island).