Definitely tell your friend to take her cat to the vet.

My dog Disney has a couple of those but hers do not hurt to touch. My vet said this summer they are benign cysts but he has me watching closely for any changes in them and if so they will do a biopsy. One thing he said to watch for is if she has any pain related to them so that must be a sign it coud be more. She has had several benign skin cysts removed over the years so I think that is why the vet is being so relaxed about these.