discoloration on hands

My son is 3 he has brownish red patches on his hands it started on just one hand and slowly over the last month it has gotten bigger.  He does not complain about them nor do they itch they are not dry they feel just like the rest of his skin.  The patches on his left hand there are 3 one between his wrist and thumb another right above that about 1inch long and 1/2 inch wide. and another that runs across the top of his had very thin but long and on his left hand it is from his knuckle on this tumb down to his wrist prob. 5inches long and 1inch wide.  

what could this be?