Scars from Freezing of Age Spots? (Photo)

I probably wouldn't have used liquid nitrogen to remove the spots. There are better options for hand rejuvenation including non-ablative lasers like Fraxel to address pigmentation and age spots and fillers for volume loss and visible veins. What you have appears to be  post inflammatory hyperpigmentation and this will almost certainly improve with time. Just keep out of the sun. 

Hi,This phenomenon is actually quite common.  The dark spots are a result of trauma to the skin from freezing, but rest assured, they will fade with time.  Be sure you are using sunscreen diligently every day, whether you are going in the sun or not.  Talk to your doctor as a prescription bleaching cream may also speed up the healing.Best wishes.