My dermotologist biopsied mole on back, said it was abnormal and could turn into melanoma and i should have it cut out. do i need to have it cut?

I guess So: I see no reason why not to listen to a professional dermatologist who trained in the study of the skin. You certainly do not want the lesion turning into a pathological condition. If you want t real 2nd opinion, you would need to go to another Dermatologist and bring the path report and get a physical exam form them visualizing the area in question. Best wishes.

Atypical?: It sounds like you are describing an atypical melanocytic lesion. These are moles that do not appear normal, but do not meet the criteria for melanoma. I recommend removing the severely atypical lesions with a margin of normal tissue around them.

YES: Your doctor has seen it and performed a biopsy. If you are uncertain, get a 2nd opinion, but don't wait!