Roderick Gordon 
Summerhouse Land [EPUB ebook] 

Time is running out for fourteen year-old Sam. He suffers from a rare inherited condition that caused terrible disfigurement to his great-grandfather and although it skipped the next two generations, it’s come back with a vengeance in him. Sam’s parents try to ensure he leads as normal a life as possible, but a normal life is difficult when your flesh and bones mutiny and bubble up into horrific growths, and pressure on your brain causes searing migraines. Then the very worst happens, but all is not lost for Sam.