Bruising on the leg without pain or itching is considered to be related to abnormalities of the blood vessel wall, coagulation factor deficiency, platelet abnormality and so on. 1. Abnormalities of blood vessel wall: when the permeability of blood vessel wall increases and the brittleness increases, it may hinder the normal coagulation of blood, such as allergic purpura, scurvy, hereditary hemorrhagic capillary dilatation, etc., which will cause patients to have leg bruises without pain and itching symptoms. 2. Coagulation factor deficiency: leg bruises without pain and itchy situation, does not exclude the cause of coagulation factor deficiency, the normal human body has 12 kinds of coagulation factors, successive activation will cause blood coagulation, when the lack of coagulation factors, may cause patients to appear leg bruises. 3. Platelet abnormality: if the patient has blood vessel injury, it will quickly adhere to gather in the injury, thus making the blood coagulation. When the number of platelets decreases or the function is abnormal, it is not conducive to the coagulation of blood, so some of the patients may have leg bruises, which belongs to the subcutaneous hemorrhage. Leg bruises without pain and itch may also have other causes, patients should go to the hospital, with the doctor to improve the examination, to determine the cause, and then do targeted treatment and treatment.