I Have A Friend That Has A 16 Year Old

I have a friend that has a 16 year old teen that has blue lips. he doesn't seem to gain weight. he is 6' 4" and is totally skinny with very white skin. he was born premature and had had several suspicious types of moles removed over the years none that i am aware were cancer (melanomia). He seems larthgic and just stays around the house a lot. i am not around him enough to see any other kinds of issues. I did very recently tell his father that he should go for blood work and a physical. As a friend I have made tbhis observastion but the parents are not educated to think that this mat be a sign of somehting major!