I have just recently noticed that my 14mth old's left arm is slightly smaller than her right. I can see the tendons in her hand and the bones in her elbow where as she has the normal chunky hand and arm in the other. She can move her hand and arm like normal and she seems to be getting circulation to them like she should. It just concerns me that it seems "skinnier" than her other arm. I called my ped and they had never heard of it and didn't seem worried. Has anyone ever heard of anything like this?