Plastic Surgery complications from being underweight?

As long as you are healthy, the weight should not be an issue.  I would search for the surgeon who you feel is most likely to give you
the best results. Look at reviews and before and after pictures on that
surgeon's website. Kenneth Hughes, MDLos Angeles, CA

Your weight need to be taken into consideration by the anesthesiologist during surgery.  Because you are small, you require less anesthesia, but your anesthesiologist can deal with that without problems.

 As long as your weight is stable and  you are in good nutritional balance, it is acceptable to undergo a  rhinoplasty weighing 90 pounds. There are no additional anesthesia risks at that weight, since the medications given are weight/ dose dependent. For many examples of closed rhinoplasty, please see the link and the video below