What are some possible causes for painless bruising?

I'd go back to your doctor. Leukemia isn't the only disease that can cause bruising. I'd be concerned about liver functions, esp. since you are complaining about pain there,which is where your liver is. The MD should be able to feel if your liver is enlarged, which has many causes.The liver has an effect on blood clotting and some diseases prolong the clotting time, hence your blood will seep into the tissues & cause bruising. Hemophilia is another disease,affecting prolong clotting time, which is also hereditary.In fact there can be other disease that run in families where the capillaries are very fragile.Some drugs also will cause bleeding and chemicals. It could be many causes so get more blood testing done. Good luck.