D.B.
Any bruise is a hematoma so I'm not sure why you call it a "hematoma bruise" - is there a specific distinction you're trying to make?
If there's some blood that has to be absorbed by the body, it may take little while longer. There could also be a small amount of scar tissue that just has to break down over time. I think it would be better if you left it alone lest you keep irritating it. These things usually resolve themselves. Try not to be impatient. You can mention it to the doctor next time you're there, but I wouldn't make a special trip if there is clearly no redness or infection from a tiny cut. I don't know how old your daughter is, but I think you can reasonably expect a lot of these injuries over the years!