"Landin," Nicole Householder called sweetly from the living room. "What are you doing?"
"Nothing," the 3-year-old shouts back.
He acts and can look like a normal, healthy child, but Landin has a very rare blood disorder that has caused him to be hospitalized constantly and led his parents to seek treatment in Texas at one of the few centers devoted to treating it.
Landin has Langerhans cell histiocytosis, a disease that affects only about nine out of every 1 million children under age 15 in the U.S., according to the Histiocytosis Association of America. The disease results from discord between two kinds of immune cells, histiocytes and lymphocytes, explained Dr. Kenneth McClain, director of the Histiocytosis Program at Texas Children's Cancer Center and Hematology Service at Texas Children's Hospital in Houston.
"What happens is that some of the growth factors and chemicals that these cells make, that are supposed to help our immune system, have been produced at really extraordinarily elevated levels and caused these cells to go a little bit crazy and cause skin rashes or holes in bones or invade the intestinal tract and cause diarrhea and a variety of other things that for some patients can be an annoyance that is easily cured and for other, very young children, can be a deadly disease," he said.
McClain's program, which is the largest in the world, is one of the few centers to specialize in histiocytosis, and it sees about 100 new patients a year from around the world. The Householder family is headed there soon.
The standard treatment is chemotherapy, as might happen with cancer, McClain said.
"For some reason, you get rid of the accumulation of cells that are causing the hole in the bone or skin rash or whatever organ that is affected and the immune system seems to get itself straightened out," he said. "For a majority of the patients, they're treated and that's it."
For about 20-40 percent of patients, however, the disease comes back. McClain, who has been treating the disease for more than 30 years, said fortunately there are now backup drugs, and very rarely will a child require a bone marrow transplant. That is, if the child even gets the correct diagnosis, he said.
"They are tricky to diagnose in some cases and easily mistaken for more common conditions such as eczema, skin infections," McClain said. "The Langerhans histiocytosis mimics a lot of more common diseases. So some people are not diagnosed for quite a long time."
Eczema was what the Householders thought as they bathed Landin on his first birthday and noticed a scaly patch on his back. Three days later, it had spread all the way down to his tailbone in a sporadic pattern. The creams they were prescribed didn't help and then patches darkened, Householder said.
"Landin started turning black and blue," she said. But doctor after doctor looked him over and came away puzzled, as he was bounced from oncology to dermatology and back. A biopsy finally brought his rare diagnosis and the doctor brought in a pack of medical students to see him, telling them, "You will probably never see a child that has it."
Because it is so rare, families have turned to Facebook for support. Householder said there are about 100 families worldwide that communicate online in what she calls "the Histio circle."
"They answer a lot of your questions," she said. "Dr. McClain is one of our friends on Facebook. He really cares about you and your child."
Landin could be facing a year of treatment in Columbia and the family will have to travel every six months to Texas for a checkup.
The disease doesn't seem to faze Landin, who a day earlier was lethargic but bounced back, ripping through all of the toys and books on the living room floor. He seems just like any other 3-year-old boy, despite what he is facing.
"He's a really sweet kid," Householder. "He's so happy. He just plays."