I have Fat Necrosis from an excision done on my face?

Does this occur only when the surgeon doesn't properly provide blood supply to the area? Or can that happen even with a perfect surgery? I need to know if he messed me up and I shouldn't trust him with my face again. If it doesn't go away and has to be excised, can a small incision be made to do that? Or would it be a big incision needing to go 20-20% beyond the whole diameter of the lump? And does fat loss ever regenerate?