There is usually no obvious reason for the ducts to become blocked, but some people do seem more prone to forming sebaceous cysts than others. It is also a condition that can run in families.

Medicare covers the removal of sebaceous cysts and other benign skin lesions if it is medically necessary. Dermatologists may consider the removal necessary if it meets Medicare’s established ...

I had one removed from my head when I was about eight-years-old and didn't have another until two years ago. Now I have three that have come up on my head beneath my hair.