Hello, You are suffering from a bump on chin. It is there since 4 years. Your bump may be indicative of an acne, scar, cyst or pseudocyst. Take care of your hygiene and wash wash with an antibacterial soap or face wash. Do not keep touching it. You should never try to squeeze or pop a cyst or pseudocyst yourself. This can lead to infection. Since it is there since 4 yrs you are suggested to get it clinically examined by a dermatologist. You may have to get few required blood tests and investigations (biopsy) done. Sometimes, putting a warm compress on a cyst can speed up the healing process by helping it drain. If a cyst is diagnosed, medical care is required. Your treating doctor may use a needle to drain fluids and other matter from the cyst. You will be accordingly treated with medications and injections to reduce inflammation in the cyst. If required it will be surgically removed. Stay away from addictions if any. If needed you will be referred to a Plastic Surgeon. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician