My primary was located on my right thigh. It was painless unless pressure was applied to it, at which time it became moderately uncomfortable. I at first mistook it for a big knot in my muscle, as it showed up about the same time that my employer started requiring us to wear safety toed shoes, and I thought the footwear change was just causing my leg muscles to act up.
Only when it didn't go away, and my wife said that she thought it had been growing bigger, did I get an MRI on it and subsequently had it removed by Dr. Rosenthal at Menorah medical center in Kansas City (he recently moved his practice to KU Medical center in KC, MO)
With the thought that it was a muscle knot, I had several massages at a salon, and, looking back, this may have expedited the metastasizing process. As far as I know, the metastasizing process is not fully understood, but mechanical agitation can trigger it in some cases.
Primary on right thigh
Re: Primary on right thigh
When the primary was finally removed, the pathologist measured it at 6.8x5.5x3.6 cm