Okay, this is a difficult subject so I will tackle it hoping that several people read this and benefit form the information.
There are benign moles and there is cancer (aka melanoma).
However, there is this category of moles that under the microscope look a little abnormal. They are not cancer or precancerous, but the pathologist does find that the organization of the mole under the microscope is a little irregular. This is a controversial topic to the point that some parts of the country do not even recognize this subtype of moles, however, most do.
Now, the field of evaluating these moles has evolved even further in some clinical circles to label these irregular moles as: mild, moderate, and severe. Not all pathologists do this, but many will.
The next challenge is to answer, "Now what?" Well, again, no rulebook here, but many practitioners I know will often leave a mild irregular mole alone if there was some left after the biopsy. Moderately irregular will be usually followed up with an excision to just ensure that it is all out. Severely irregular is either completely cut out, or even cut out with 0.5cm margins. This is to ensure that just in case the pathologist may have not made the call of melanoma, and it was melanoma, we did an appropriate treatment (kind of like insurance). Would any of these moles have turned into melanoma? For mild and moderate the answer is most likely no and that it was just a signature of the moles you make. Severely irregular, some think that this may be the only 'precancerous' mole, others do not think this. In the end, We have no idea. Welcome to the art of medicine.
So, that is a rundown of irregular moles that I tell my patients all the time.
Good luck and I hope it helped.