MY MOTHER HAS A LUMP ON HER LEG CLOSE TO

MY MOTHER HAS A LUMP ON HER LEG CLOSE TO HER KNEE THAT IS HARD, NOT PAINFUL AND ABOUT THRE FOURTHS THE SIZE OF A LARGE EGG. SHE HAD AN ULTRASOUND AND THEY COULD NOT DISTINGUISH ANYTHING FROM THAT. SHE HAD AN MRI AND HER DOCTOR CALLED HER WITH THE RESULTS. HE IS PRETTY SURE IT IS CANCER. SHE WILL SEE HIM ON 02/13/2017 TO SET UP A BIOPSY. WHAT KIND OF CANCER WOULD OR COULD THIS BE? SHE HAS HAD THIS LUMP FOR A YEAR.