Hi thanks for posting
There is a rough patch of black skin on your hand since a few weeks.
It could be post inflamatory hyperpigmentation
, only sunscreen wont help. you can use the following
creams like hydroquinone ,kojic acid, or glycolic acid
sunscreen may be used during the day
steroid cream like momatosone or fluticasone twice a day.
spot tca peel or glycolic peel may be helpful
since it is spreading, i advise you to contact a dermatologist
hope this helps you