Cyst on back of babies head?

Has anyone discovered a cyst on their babies head? What was the treatment/what was done about it? She is about a month old and we have an appointment coming up with her dr so I plan to bring it up. I just noticed it today, as I was feeding her I was gently rubbing the back of her head when I felt a small round squishy thing that moves around just above her neckline on the back of her head just about where her hair ends. It doesn’t seem to bother her when I touch it gently but I’m concerned about what it is. It reminds me of how a cyst feels. Has anyone found a cyst on the back of their babies neck or head before? Did they need to have it removed?