Whats are the Causes of lumps in the pennis

My name is Dominion, am from Okigwe, I'm 18 yrs old,
Earlier this week I noticed a soft painless lump on my pennis with a very tiny opening, it scratches sometimes, I don't know what the cause may be. The last time I had sex was last year November, though I've been masturbating, I've been on research to find out what could be the cause of the lump but I haven't found anything