three cyst in shoulder and one on the cavical

I am scheduled for surgery on the 24th  I am worried that this might be cancer. I am told it is rare but it can happen. I have a hard bump on my cavical that they thought was a bone spur after the MRI they said it is a cyst and I have three more inside my rotary cuff. It probably is nothing but it worries me. They say it is rare to have a cyst in the shoulder. I have been on line and there is so much information but nothing specific about shoulders they just talk about wrist . Any input would be helpful.