Hello, I can understand your concern for the small large bruise on the elbow. You have not mentioned your age, gender and any related history of medications so that I could have helped you best. Most commonly these kind of bruise are basically a normal process because of friction or can also occur due to any medications too. So if you are taking any medications then should consult a doctor. In my patients with your kind of situation I generally go for certain tests including bleeding time, clotting time and platelet counts. I prescribe vitamin C tablets in case if we find recurring bruises. You can take further guidance from a dermatologist. All the best.