Ossifying fibroma

Hello. A friend of mine had this knee pain for months; she recently did x-rays and they found a "ossifying fibroma". It was written that there's a radiolucent area with sclerotic margins for what concerns her femur. Now she has to do other exams to be sure. My question is: are x-rays reliable when it comes to this? I'm so scared they were wrong and she has something malignant. I looked at other fibromas x-rays on the Internet and they look very similar, but I don't really know, since I've read they aren't painful at all while her pain is really strong but easily goes away with painkillers. Thank you in advance.