Does a completely removed potential precursor to malignant melanoma atypical nevus return in same place? does it return as a malignant melanoma?

No: If it was removed completely, it will not return. This is why it's good to take margins. If it does recur at the site, it will probably still be a benign lesion, but keep an eye on it. The most important thing about a diagnosis of atypical nevus is that it warns you're likely to get a melanoma someplace else. Keep an eye on all your skin (partner, dermatologist) and quick removal will save you!

No: If completely removed with adequate margins it shuoldn't come back.