Dark Patch on Penis Shaft

About four years ago I noticed a darker patch of skin located on my penis shaft.  More specifically it's located on the very bottom of the shaft, starting where the shaft meets the scrotum and traveling up towards the head a little ways.  It's oval in shape and very slightly indented.  The color is a bit darker than my usual skin tone.  It is sometimes slightly itchy or uncomfortable enough that I'm sometimes just vaguely aware of it.  The patch has stayed the same since I discovered it, it hasn't spread or changed in appearance at all.  For awhile I considered the possibility of a birthmark, but thought it strange I hadn't noticed before.  I sit in front of a computer for a least 8-10 hours per day as my job.  I usually sit in the same position with a poor ventilated chair.  Is fungus a possibility?  Also, I would like to hear your thoughts on skin cancer.  I'm in my early twenties, and so it's probably unlikely, but it's worrisome all the same.

I notice that if I go a few days without showering, there is a small amount of wax-like buildup stuck to the hairs growing through the patch of skin.    

I noticed when it appeared that I had moderate jock itch.  Another thing I noticed, which may be completely unrelated, was the appearance of a few varicose veins at around the same time.  

Thank you.

[Alan Rockoff, MD]

Most probably this is either a freckle or pigmentation from chronic irritation.  I do not think it represents anything serious or anything you'll need to do anything about.  Show it to a doctor next time you see one.

Take care.

Dr. Rockoff

[ilikehats]

Thanks for the reply.  Something I forgot to mention was the size of the patch.  It's approximately 1" x 0.5".  I don't know if this makes any difference. Also, Is there anything I can do to regain the skins normal appearance?  You mentioned chronic irritation, would wearing looser fitting clothes help or possibly changing my sitting habits to avoid repetitive wear?

Thanks so much.

[sufian_5m]

i  have the same thing, do you have a cure for it,,,,