A Saskatoon woman is speaking out about her 10-month-old daughter's battle with Langerhans cell histiocytosis, a rare disease that is often difficult to diagnose.

Jackie McMillan says her daughter, Isabella, lost nearly half of her body weight before she was recently diagnosed with the disease, which attacks various parts of the body.

Langerhans cell histiocytosis usually affects children and can be fatal. There is no known cause of the disease.

McMillan said in Isabella's case, doctors initially thought the girl had acid reflux and would eventually grow out of it. The disease affected her scalp, skin and one of her bones.

"Of course I'm upset with that, but I don't blame them for not having a diagnosis because they're not educated," McMillan told CBC News in an interview.

"This disease is so rare that a lot of doctors don't even know that it exists."

It's estimated that about two to three children in Saskatchewan are found to have Langerhans cell histiocytosis each year.

Dr. Roona Sinha, a pediatric oncologist in Saskatoon, said it is hard to diagnose Langerhans cell histiocytosis because its symptoms can look like a lot of other things.

"You can present with just a rash, and rashes you can get from a lot of different reasons," Sinha said.

"So sometimes it's very hard to figure out if this is a rash caused by Langerhans cell histiocytosis."

Sinha said more research into the disease is needed.

As Isabella needs to undergo more tests and treatment, her mother is organizing a fundraising event to raise awareness of Langerhans cell histiocytosis.

The event, called "Hands for Histio," will take place Sept. 20 at Lydia's Pub in Saskatoon.