Could be viruses or growths occuring in your body. Since growths and tumours have many different origins and can be either benign or cancerous it is important to seek medical advice and have them removed professionally or biopsied. It is difficult to look at a growth and determine what it is unless some tests are done. If that were the case alot of doctors would be out of business if someone could look at a growth and accurately predict what it was.
Do not attempt to take them off yourself because if you damage yourself you will have to seek medical attention for that too.