Possible Cyst?

I'm not sure if this is the best forum for this question, but here goes:

I am a 29 year old, circumcised (at birth) white male.  I'm otherwise healthy and have tested neg. for any STD's.  Approx. 2-3 weeks ago, my girlfriend noticed a small, round (maybe dime size) raised bump beneath the skin of my penis.  It is located near the base of the shaft on the top right side.  She noticed it immediately following sex as it appears most prominent when I have an erection.  It's not nearly as visible in a flacid state, but you can still see it if you're looking for it.  There are no abnormalities on the surface of the skin; everything seems normal.

To describe it best, I would say it looks cyst-like.  It's soft to the touch and it appears to move freely beneath the surface skin.  To be honest, it's quite plausible it may have always been there and I just never paid attention.  Nonetheless, I am completely freaked over the deal and very anxious.  I have since made an appt. with my physician, but can't get in for a couple of weeks.  

I guess what I'm seeking is a little reassurance that this is probably harmless.  I know it's not wise to self-diagnose via the internet, but I've succumbed to that temptation and I'm scared it may be cancer or whatever it is, cancerous.  On to my questions:

1) I've read online that penile cancer in circumcised males is quite rare, almost never, in fact.  Is this true and should I even worry about it?  Wouldn't symptoms typically manifest on surface of the skin near the head?

2) Is it possible that whatever this is may be just part of the penis itself, ie) a slight abnormality or bump in the actual shaft an not necessarily a growth?  Maybe something that's always been there and just never noticed until brought to my attention?

3) I know without being able to see it, you can't make an accurate diagnosis.  But from what I've described, does this appear to be a cyst?  If so, is it harmless and how would it be treated?

Thanks!

[Alan Rockoff, MD]

It's either a cyst or nothing at all.  You're right about the rarity of penile cancer in circumcised males.  The doctor won;t have any unpleasant news for you, I'm sure.

Best.

Dr. Rockoff

[npk]

Thanks for your help!  I feel much better about this...

If it was determined to be a cyst, how would that be treated or do they typically go away on their own?