My friend has a weird cyst like bump by her hairline.What could it be?

I've looked on wikipedia and google with it's description. She thought it might be a goiter, but it isn't since it's at the back of the neck.
Some insight please. She used to have lots of smaller lumps on her neck when she was little, but the doctor said she was fine then.My friend has a weird cyst like bump by her hairline.What could it be?
It could be a reason to visit a dermatologist. But if you want to read up on something, look up sebaceous cyst. They are common around the hairline.
What could it be - it could be serious!
Tell her to go to the doctor again!
All lumps should always be checked but in the meantime my son had had one and the dr. said it was an ingrown hair. Again I would get it checked