Hi Your daughter seems to have developed a bruise over the leg. This basically develops due to an internal bleedinIg secondary to any kind of trauma. This type of skin lesion usually takes some time before it completely heals. You should avoid touching the affected area . Oral vitamin c supplements are given sometimes so as to speed up the healing process. In most cases , nothing really needs to be done. In case the lesion tends to persist or if more similar lesions develop , then she might need to be assessed by a dermatologist . Hope it helps Dr Geetika Paul