Conversation: The conversation between human and AI assistant.
[|Human|] My 19 yr old sister has a golfball sized lump at the back of her head. At the base of the skull, top of the neck. I was brushing her hair when I noticed and started rubbing it. My sister also noticed and said it felt strange for me to touch it. She knew it was there, said it had been there for a long time and that she thought it was normal. I m wondering if we should be concerned.
[|AI|]  His appreciate your concernLooking at your history there could be two possibilities either sebaceous cyst nape of the neck or a Desmond cyst scalp I would like further information to help you better like duration since it has present size slipping sign cough impulse presence of punctumplease visit a surgeon for detailed examination and confirmation of diagnosis Hope I have answered your question thanks for using ChatDoctorgood luck