What are EGIDs?
A growing number of children and adults suffer from a chronic and complex group of diseases described as Eosinophilic (ee-oh-sin-oh-fill-ick) Gastrointestinal Disorders (EGIDs). These disorders are characterized by having above normal amounts of eosinophils, a type of white blood cell, in one or more specific places anywhere in the digestive system. EGID is further subdivided into organ-specific diagnosis. For example, Eosinophilic Gastritis means eosinophils infiltrating the stomach. “itis” means inflammation. While visual inflammation is not always present, inflammation may be apparent under the microscope.
- Eosinophilic Esophagitis (EoE): high numbers of eosinophils occurring in the esophagus.
- Eosinophilic Gastritis (EG): high numbers of eosinophils in the stomach.
- Eosinophilic Gastroenteritis (EGE): affects the stomach and small intestine.
- Eosinophilic Colitis (EC): describes the occurrence of high numbers of eosinophils in the large intestine.
Above normal amounts of eosinophils within the digestive system may or may not be enough to diagnose a person with an EGID; what the eosinophils are doing while present is equally important. Currently, without a standardization of diagnostic criteria, medical institutions use different variations of the same criteria including: inflammation, numbers and activity of eosinophils, and symptoms.
The increased numbers of eosinophils present does not always indicate EGID. Other inflammatory cells and other inflammatory changes that include eosinophils, but which are not exclusively eosinophilic, are common in other inflammatory diseases such as Crohn’s disease and ulcerative colitis.
Frequently Asked Questions
Why don’t we hear more about EG, EGE and EC? Other than a different part of the GI tract affected, are the disease processes different? When can we expect definitions of the “non-EoE” EGIDs? Can you have EoE AND EGE? Is that treated differently than EoE alone?
The above series of questions are posed frequently and are legitimate concerns. We can approach the answer from several different angles.
The stomach, small intestine, and colon are completely different organs when compared to each other and when compared to the esophagus. Their functions are highly individualized and the lining layers look completely different under the microscope. The nature of the symptom that arises when those organs are inflamed is different (e.g., trouble swallowing if the esophagus is involved, diarrhea or pain if the colon is inflamed), even if eosinophils are the predominant inflammatory cell seen in excess under the microscope. The treatment is different depending upon the location and whether or not the disease is generated by exposure to particular foods (i.e., food allergy). Eosinophilic GI diseases affecting the stomach, intestine and colon are less likely to be allergic in nature than EoE.
The conditions that are labeled EG and EC and EGE now are diagnosed histologically based on the experience of the pathologist. It is possible for several pathologists to review the same slides and come up with different impressions or diagnoses. Great care must be taken when one is ‘diagnosed’ with EG or EGE or EC to be sure that the diagnosis is as correct as can be in the absence of diagnostic criteria. Marked or severe inflammation with eosinophils is not difficult or mysterious to diagnose—the real problem comes when the inflammation is mild or close to what is considered normal, because the difference between normal and ‘disease’ can be subtle under the microscope. The question that then arises is: are these subtle changes responsible for the symptom(s) and indicative of disease? The answer to that may not come from biopsy, but from the response to directed therapy.
EoE is defined as eosinophilic inflammation limited to the esophagus, so one can’t have EoE and EGE together as separate disorders. It is common, however, to have EGE with esophageal involvement, which is one disease, not two.
Eosinophilic esophagitis (EoE) is far more common than the eosinophilic gastrointestinal disorders that affect the rest of the GI tract. That single fact makes EoE easier to study because there are more patients available to participate in research. To be valid scientifically and statistically, formal research studies generally require large numbers of subjects, so that the results are both correct and applicable to the broader population. Research in a common condition also has the greatest impact because more patients benefit from the study. Because there is a formal definition of EoE that includes diagnostic criteria, research studies can legitimately include patients who meet that definition.
The same things are not so true for eosinophilic gastrointestinal disease ‘south’ of the esophagus. The relative number of patients is small, perhaps too small to do a scientifically valid study in a single geographic region. In addition, because there are not formal diagnostic criteria for EG (for example) as there are for EoE, there may well be multiple conditions that look the same under the microscope and could legitimately be labeled EG by the pathologist, but which are indeed different disorders. Including patients who really have different diseases in the same study may invalidate the study.
The good news is that it is possible to apply some of the research techniques that were learned for EoE to the stomach and intestines, so we will begin learning more about EG/EGE/EC as time goes on (and it is being done, just not published yet). To accumulate enough patients to make a study valid will necessarily take longer than it has for EoE. Because it is likely that the diseases share some but not all features with EoE, additional study of the GI tract will likely be required to fully characterize each condition.
The work that is being done to characterize EoE will help figure out EG/EGE/EC. There is not yet a formal attempt to create diagnostic criteria, as there has been ongoing for EoE, but that likely will need to be the first step in pushing forward the agenda to make EG/EGE/EC equally well-understood.
Answer provided by Philip E Putnam, MD, Professor of Pediatrics, Cincinnati Children’s Hospital Medical Center, Medical Director, Cincinnati Center for Eosinophilic Disorders
- EGID Brochure
- Eosinophilic colitis: epidemiology, clinical features, and current management (open access review article)
© American Partnership for Eosinophilic Disorders (APFED) 2004-2016 All rights reserved. Content may not be reproduced in whole or in part without express written consent from APFED. Contact us at firstname.lastname@example.org. Authors: Wendy Book, MD, and Phil Putnam, MD