Three weeks into a final project for her senior biology class, Jessica Terry, 18, made a discovery that years of tests by gastroenterologists and pathologists had failed to make.
"I yelled for my teacher, 'Ms. Welch, come in here, you have to see this!'" said Terry, a senior at Eastside Catholic High School in Bellevue, Wash.
The slide Terry had under her microscope held a slice of her own intestinal tissue. Magnified on a screen was a large, darkened clump of cells surrounded by red dots of stained white blood cells in the process of engulfing surrounding cells -- a granuloma, one of the potential indicators of Crohn's disease.
"I think I looked at the right immune response in my tissue and where it was worst," Terry said. "I didn't go into it trying to find Crohn's. I went into it looking for abnormal things to show in my project."
Terry sent her samples to pathologists who confirmed that her finding was a granuloma. Coupled with her symptoms, Terry's self-diagnosis was Crohn's disease.
Terry suffered from an indeterminate gastrointestinal disease for about 10 years. Doctors wavered between diagnosing her with Crohn's disease, characterized by extreme inflammation that can occur anywhere along the gastrointestinal tract, and ulcerative colitis, characterized by inflammation in the upper lining of the large intestine.
Both Crohn's disease and ulcerative colitis can cause fever, cramping, diarrhea, weight loss and pain. Terry had all of these symptoms through middle school and parts of high school. Such similar symptoms can make them difficult to distinguish from each other.
"There was nothing in the pathology [of the disease] that would waver one way or another," said Colleen Terry, Jessica Terry's mother. "And the treatment was the same, unless she needed surgery."
Terry said her daughter had been in and out of remission for about three years but was doing well, medically, on an immunosuppressant called Remicade. Jessica Terry said that, Because she was responding well to intravenous treatments of the drug, Jessica Terry said, she had stopped getting frequent biopsies of her intestinal tissue. The slides of her tissue that she studied in her biology class were from 2004.
Although Jessica thought that her positive response to Remicade should have pointed definitively toward Crohn's disease, the illness was more complicated. While Crohn's disease is often called an autoimmune disease, in which the immune system attacks healthy cells, it is not.
Crohn's disease is an overreaction to normal foreign bodies in the intestines, such as bacteria. The resulting immune response -- inflammation due to white blood cells -- can destroy surrounding healthy cells, causing digestive problems.
Remicade worked for Jessica, but its powerful immunosuppressant properties means it works for those with ulcerative colitis as well. And, for some, Remicade does not treat either Crohn's disease or ulcerative colitis. Jessica felt better but still had no definitive diagnosis.
"You wouldn't really want to make a diagnosis based on response to treatment," said Dr. Bruce Sands, acting chief of Gastroenterology at Massachusetts General Hospital.