<s>[INST] I have a small lump on my right testicle about 2mm across. I have had this lump since i was about 12-13, and i am now 17 nearly 18. The lump has enver grown in size and is usualy not there. It only apears once every few weeks (5-15) and only apears for about a day or less. It is a little painfull as well but not unbearable. I have also found it is more common when i wear tighter jeans and/or underwear. Should i worry? Or is it more than likely just a cyst? [/INST] Welcome to Chat Doctor .1. The history suggest me that it's an inguinal hernia - on and off swelling in the scrotal sac which disappears after some time.2. And clothing do effect the swelling which means pressure effect also favors in terms of hernia.3. Possibilities of cyst can not be there, because if there is cyst there will be for all time not fluctuation in size.4. In this case I would recommend getting an ultrasound scrotum done when you have the swelling.5. It will exactly help to find out and differentiate actual pathology - weather mass, cyst, hernia - where it's existing from and where it's extending to - it's a good tool for scrotum and testis.6. You should worry until you find out cause - but nothing is scary in your history. Hope it helps you. Wish you a good health. Anything to ask ? Do not hesitate. Thank you. </s>