Updated

In 2010, Deryn Blackwell was diagnosed with acute lymphoblastic leukemia – and he and his family were prepared to fight the disease.

But, two years later, Deryn, 13, learned he had relapsed, and a new diagnosis came with it: Langerhans cell sarcoma,  a cancer so rare, there are only six cases in the world, edp24.co.uk reported.

Langerhans cell sarcoma is marked by these signs and symptoms, according to rightdiagnosis.com:
• Enlarged lymph nodes
• Mass under skin
• Enlarged liver
• Enlarged spleen
• Bone mass

It is thought to be caused by having another type of cancer or lymphatic tumor.

Doctors think Deryn may be the only person to have both cancers at once.

Deryn is at the Bristol Royal Hospital for Children in the U.K., and doctors hope a bone marrow transplant will save his life.

“We are prepared for at least three months at Bristol,” said Deryn’s mother, Callie, who added her son has been very brave throughout this ordeal.

Callie said doctors decided the best way to treat the cancers is with a “R3 protocol, which involves 12 days of conditioning, total body radiotherapy and targeted radiotherapy to his throat, which is where they found the tumors.”

If all goes well, the bone marrow transplant would occur on March 1 – and Deryn would be placed in isolation for three to seven months.  At this point, Deryn will have less of an immune system than that of a newborn baby.

Callie, and her husband, Simon, have raised nearly $11,000 through their foundation, DoEveRYthiNg.

Simon said Deryn is “100 percent certain” he’ll recover, and hopes to become a doctor one day.

Click here for more from edp24.co.uk.