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Selected images from an ankle MRI show a heterogenous, enhancing, cortically-based lesion in the posterolateral distal tibial metaphysis. There is adjacent bony sclerosis as suggested by hyposignal in the medullary cavity on T1WI pre-contrast images. There is enhancement in the adjacent bone, periosteum (which is smoothly thickened) and even soft tissues. Osteoid osteoma is the most likely diagnosis, but CT can help better delineate a nidus.