<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have a mass on my neck that seems to be getting bigger. Also, the skin over it looks abnormal and swollen with some moles. What might be going on?  <response>: Based on your symptoms, it sounds like you have a sebaceous cyst. It is a common benign growth filled with sebum, a cheesy, oily substance that occurs from the oil glands in the skin. We can remove it with a minor surgical procedure. 