Large under skin lump on penis shaft?

[WorriedALot976]

So I got this large lump on my penis that doesn't hurt but right now I am feeling slight pressure on it after I mastrubated yesterday. I have had it for approximately a month now. It isn't big on pictures but it gets bigger after mastrubation, and when penis is hard can't be noticed. It's felling of hardness when i touch it is the same as the rest of penis. Could somebody tell me when they think it might be or they know what it is and if it is serious?

[purple1234567]

For any abnormal lumps anywhere on your body, I'd recommend going to a doctor to get it checked out.  Good luck!

[WorriedALot976]

Sorry double posted, first time asking a question, here is the question with pictures: http://www.medhelp.org/posts/Dermatology/Large-under-skin-lump-on-penis-shaft-/show/2987937