Re: Dysplastic Nevus - what does it mean?
A dysplastic nevus is what is called an atypical mole. Simply put: these are usually benign, but may resemble melanoma. Almost 10% of Causasions have these types of moles (so you are not alone), and if you have one, you are at an increased risk for developing a melanoma. Note: This does NOT mean you WILL develop melanoma.
Moles/skin cancer is such a weird thing. A mole can go along for years just sitting there, looking the same year after decade. Then, all of a sudden, and for no reason, it will suddenly begin to change in some way. It's almost as if your body is a canvas, and the painter isn't finished yet. This is when moles are serious and should be looked at (and it might still not signify melanoma, go figure). Other times, you might have a mole that has been atypical for some reason (size, shape, border) for most or all of your life, and for some reason, a doctor will have a "feeling" about it and want to remove it. Chances are, if the mole has been there a long time, and has not been changing, it's benign and you will be okay.
As far as changes coming but they couldn't tell - I would find that highly unlikely. I'm a little confused by your doctor wanting to excise the area. If the biopsy doesn't reveal any melanoma, what's the point? Or does this mean the derm wants to re-do the biopsy? In melanoma-speak, an excision means to remove the surrounding tissue of a mole - something in the neighborhood of 6 centimeters. I have a 3" scar on my knee where my 1/8" diameter melanoma was located, just to give you an idea. So perhaps we are using different terms here.
If the biopsy has returned clear (no cancer cells), then there should be no further treatment. You should do regular skin checks, though. If the biopsy returned with evidence of cancer cells, then you will need to have a wide excision - what I mentioned above - and, if clear margins are determined (no cancer cells in the surrounding tissue) you will be staged, depending on the depth of the skin cancer. HOWEVER, dysplastic nevus is NOT EQUAL to skin cancer, so I'm more than a little confused as to what your derm is looking to do.
I'm not sure if this helps much...I hope it does!