What Could Dry Patches Of Skin On Biceps Of Arm Suggest?

my two year old had a dry patch of skin about the size of a half dollar on the outer part of her bicep on her arm, it just feels like a sport of dry skin but didnt know if i should be worried, my ex husband just pointed it out to me and it has been there since monday he said, i made an appt for tomorrow for her.... any ideas