A bruise is a black-and-blue mark caused by bleeding into the skin from damaged blood vessels. Many children older than one year of age develop bruises associated with accidental injury and physical activity.
Most bruises are not a cause for concern and will go away on their own. However, bruising can be a sign of an inherited bleeding disorder, illness, or non-accidental trauma (child abuse).
Bruises may be abnormal if they occur spontaneously without explanation, if they are in other places than the lower legs (“unexplained” bruises on the shins are usually normal because children often bump this area and then forget that they bumped it), if they are larger than a quarter in size, and if they are lumpy rather than flat.
Bruises may also be abnormal if they are larger than expected for the degree of injury.
