It is harmless condition in which patches of skin become darker in color than the normal surrounding skin:
Aloe Vera and Red Lentil Mask
Red lentils are rich in antioxidants that are known to be good for the skin.
Soak 50 grams of red lentils overnight in a bowl of water. Use a blender or food processor to create a fine paste.
Add aloe vera gel to the mixture
Apply the paste evenly over your face and leave it on for 20 minutes.
Rinse with cold water and pat your skin dry with a towel.