Cancer Survivors Network

My mother has always had these "fatty tumors" her entire life. They pop up, she'd have them removed, later on another would pop up, the cycle continued. None of which have been cancerous. They've been removed and they've all been benign. In June of 2010, she had a golf ball size tumor on her right hip/thigh area confirmed on an MRI. She complained that this tumor had grown and her Dr. requested another MRI. So it's now 16 cm x 3 x 3(give or take). The report also stated "positive evidence of liposarcoma". Without having a biopsy, what would make them determine this? Her Dr. has been her Dr. for over 15 years and she said his reaction when he read the report was "oh my god", something she's never heard him do before. He even went as far as immediately talking with another one of her Dr's via conference call about the actual tumor removal (because it had grown so quickly from June)at either MCV (VA. Commonweath University) or Duke. She is scheduled for a biopsy on Wed. 2/16. I have a million questions. I've read a lot of information on here, on-line, etc. I read up on these 2 hospitals, and Duke seems the better choice. I guess without the biopsy to confirm/rule out, I'm just torn up as to why that was stated on the report. Is that common? Is it that distinct that they would know it if they saw it right off? She is a 54 year old woman in pretty good health. I wouldn't say she's top notch healthy, but very active. I just need to know as much information as possible and if anyone has had any history with this type of cancer in Va. and where they were treated. Thanks in advance.
~A