lipoma vs. liposarcoma

I have had a lump on my leg for the past year.  I showed it to my pysician (actually, physician's assistant) and she said it looked like it was just fat.  She didn't make a big deal about it.  I continued to be concerned about it because it just didn't seem normal to me. the lump is on the side of my leg above the knee and is about a 5 inch oval. It is soft.  I have some spider veins around the area and thought maybe they had something to do with it so today I went to a vascular surgeon.  She thought that it was a lipmona and suggested I see a surgeon.  After researching "lipoma" on the internet today I noticed that lipomas don't seem to occur on the thigh area, but liposarcoma's do.  needless to say I am now extremely scared that I have a malignant tumor.  I called to make an appointment with my regular physcian for tomorrow.  I am going on vacation to celebrate my 25th anniversary on Friday.  I hope I can relax and put this out of my mind.  My question is , are lipoma's found on thighs and how likely is this to be a liposarcoma if I have had it for at least a year?  I feel fine. Are there any other symtoms (symptoms)?  What course of action would you take?  Please help, I'm full of worry.