I was told i have a small cyst...that may turn into cancer?

Okay so i went to get a sonogram done on my thyroids, because my doctor mentioned that my left thyroid seemed a little swelled. But i got the report back today and was told that my thyroids are the normal size, but that i have a 3millimeter cyst on my right thyroid. She also mentioned that it could turn out to be cancer? Im extremely nervous and am not sure how to take this... What does this mean and what should i be expecting...especially since cancer does run in my family??