According to the University of Washington, a sclerotic lesion of the bone usually results from a slow-growing bone disorder that allows the bone enough time to attempt the formation of a sclerotic area around the offender. Dictionary.com states that sclerosis is a hardening of tissue.
Bone can react to a disorder by creating more bone tissue or removing some tissue, according to the University of Washington. Sclerotic lesions are not typically seen when bone reacts to a rapidly-progressing disorder, because the bone only has time to retreat in defense. Analysis of the lesions by a qualified professional should provide insight into the specific disorder affecting the bone.