Unexpected Results

Hi......
My name is Patti D., 12 years ago, the Spring of 2012, I had a routine mammogram at the Mayo Clinic in Rochester, Minn. When I was called into the Doctors room, I had a diagnosis that left me dumbfounded. They discovered a bad lymph node, in my left axillary (armpit).
I had a 6-point biopsy that divulged it was a "poorly differentiated squamos cell carcinoma", Now I was told it was a form of skin cancer.
I chose to have surgery to remove the bad lymph nodes and any tissue that was affected, after having a long talk with the surgeon.
After surgery I was told that the surgeon could not find ANY Cancerous nodes or tissue present. He was amazed. He suggested along with the Doctors that I should undergo 5 weeks of radiation, to eradicate any possible cancer. They were never able to find a primary cause.
No sign since then except I am noticing a blackish vertical stripe on my thumbnail. I have read that this could be a sign of skin cancer. Anybody know ??