Vader suffers from Acute Neumonoultramicroscopicsilliconvolcaniconiosis (yes, it's and actual illness).
It's a disease where lung tissue is damage or scorched away from inhilation of microscopic volcanic ash and/or molten rock. I'm guessing he did most of the damage when he was gasping for air heavily while clawing his way back up the black sand.
Originally posted by PVS
yes, i think that question is answered...but what about that huge gash on anakin's head we see in ep's 5&6?i know they showed it on mustafar...but its as if the gash just appeared...i dont get it. if its a result of the burning why didnt his whole head turn into that? only thing i can this is somehow the skin on his skull tightened up and cracked down the middle from the fire...
I noticed that scar and was wondering about it too. The Large gash behind his head. I would guess that it may have occured during the twenty some years before EP5,6. But there is no one who can really stand up to someone like vader. Maybe the Emperor got pissed off at him one day for showing to much forgivenesss for his admirals or someone, then swiped him with his lightsaber for punishment.