Lump behind the knee!

[jessieblue]

Hi guys, just found a lump at the back of my knee and am terrified its cancer!! I noticed the back of one leg seems larger behind the knee than the other when my let is fully straight. I have poked and prodded, but now I am convinced its a tumour. (My sister had a cancerous tumour in her leg above the knee when she was 21, 30 years ago. Maybe I have the same gene and have a tumour as she did. Please help I am really worried!!

[Cell block H fan]

How big is it? No chance its a varocous vein? My ex had one on his leg, but it was on the front near his shin, about the size of a large marble. They're more common on the back of the knees though.