Itchy thighs and bruising after scratching. The damage to the endothelial cells of the capillaries may cause damage to the endothelial cells of the capillaries, and the damage to the endothelial cells may lead to the leakage of blood cells, including red blood cells and white blood cells, from the blood vessels. What you see with the naked eye is actually a bruised state, and this bruised state is the state of subcutaneous bleeding, so when you encounter this situation, try not to scratch excessively, because scratching external influence will damage the subcutaneous blood vessels.