Worried about daughter's biopsy results

HI, I am writing because my 3 year old daughter had a very unusual mole removed for biopsy.  It was 2 different colors (dark brown in the center, and light brown all around that), slightly larger than a pencil's eraser, and had an irregular border.  I went in for her follow up today, and was told that it was a Dysplastic Nevi with atypical cells.  The doctor then went in and called the doctor at the lab that did the biopsy to see if he thought more should be removed.  They both decided to send the specimen to another lab (he said one of the best for skin cancers)for a second opinion.  When I asked if the mole (which is on her head, by the way, above her left ear) was caused by sun exposure, he said no.  I don't remember her being born with it.
I am very concerned about these atypical cells, and what that means.  I also wonder if it's possible to mistake cancer cells as atypical.
Are atypical cells pre-cancerous?
Also, what causes them.  I am very scared of melanomas, we do have a family history of them, but are they only caused by sun exposure?  He said this mole was not caused by sun exposure.
Anyway, I was wondering if you think the first results are probably pretty reliable, and I shouldn't be worrying.
One more thing, if it does end up being just atypical cells, will they remove more until they get a clean margin, or is it safe to have atypical cells left on the skin.
Sorry so many questions, I am scared to death, and have to wait 3 weeks to get these results back.
Thank you in advance,
Erin.

[Alan Rockoff, MD]

I don't blame you for being scared, but I'm confident you won't be getting bad news.  Here's why: the therm "dysplastic" is a vague and unsatisfactory term, because nobody knows exactly what it means.  Basically, it means "finny looking," but how funny is funny depends among other things on who is reading the slides.  I'm sure the laboratory to whom your doctor sent the slides for another opinion is staffed by experts in skin pathology--their reading is going to be the one that counts.  If they think the mole is dysplastic enough to be taken off completely just to be sure (that's the most they might recommend), it's because we don't know whether being dysplastic is precancerous--it may not be but it just seems prudent not to wait around to find out.  Or they might just say that it's a little dysplastic and not to bother doing anything.

But when you get the final reading and do whatever is needed (if anything), I'm confident you'll be able to put the whole matter behind you and your daughter.

Take care.

Dr. Rockoff

[erin-h]

Thank you, Dr. Rockoff...you have eased my mind considerably.  I thought he was sending it there just to be sure it wasn't cancer.  If they want to remove more, I don't mind at all.
Thank you!
Erin.