By Emma Dodds
Deryn was ready to die after four years of treatment (Credit: Twitter/ Deryn Blackwell)
As a parent, your job is to protect your child from harm.
However, it’s not always possible – and that’s the devastating reality that Callie Blackwood had to endure.
But in January 2012, Deryn’s throat began to hurt and he had his tonsils removed, which were found to be cancerous.
It took the doctors a few days to diagnose what type of cancer this was – because they’d never seen it before.
The cancer was found to be Langerhans cell sarcoma – which is so rare that only five people on the planet have ever suffered from it.
The one in seven billion cancer is aggressive, and so little is known about it that even Deryn himself isn’t sure how to describe it.