Bump underneath penis

Hello, i have recently discovered that i have a bump underneath my penis.  it is about 1cm in diameter and it is very visible when i am erected.  i do not know what it is, it does not hurt at all, it sometimes bleeds and the first time i noticed it, there was white stuff coming from the bump.  it is located about 1 inch from where the bottom side of the penis starts to connect to the testicles.  i went to the doctor a couple of months ago and he said that i did not have hiv or std's.  but back then i did not have the bump.  it is almost invisible when i am not erected and it looks like its growing.

thanks for your help

i do know know what it is, can you please help?

[H. Hunter Handsfield, M.D.]

Probably a sebaceous cyst, i.e. a glorified blackhead.  Perhaps infected intermittently.  Almost certainly not an STD and not a serious health threat.  But you should see your doctor; it probably needs to be incised and drained or perhaps surgically removed, to prevent a more serious infection in the future.

Good luck--   HHH, MD