My Wife Has Been Told She Has A Spot On

My wife has been told she has a spot on her ovary from an ultrasound while looking for a bleeding problem for months. She had a hysteroscopy to remove a rather large (benign thank God) polyp 10 days ago and going back Friday for another ultrasound to look at ovary. My question is what are causes and what are her chances it could be bad news this time?