Large hand size can be a sign of acromegaly but he is too young to have that.
Google a picture of Killer Kowalski, he had acromegaly that cause big hands, it's usually when HGH gets produced (or used) well into adulthood and is usually caused by a pituitary tumor. Giantism is when you over produce HGH in childhood and end up freakishly tall, but you don't get the facial deformities and over large hands.
Sorry I have to add this in
Let me go on like I
Blister in the sun
Let me go on
Big hands, I know you're the one