Small intestinal biopsy is the "Gold standard" diagnostic test for celiac disease within the medical community.
There are lots of controversies in the diagnosis and classification of the observations found in a sample of small bowel. To aid in more accurate diagnosis, there is a call for a standardized report scheme for pathologists.(1)
Dr. Marsh made such an attempt back in 1995 or so and the March protocol was adopted by some. It was updated and simplified. This protocol looks not just for whether the villi are absent or shortened or normal length, but also for the condition of the intraepithelial area. And the criteria are different for the different parts of the bowel. I have never seen a Marsh scale on any SB biopsy report.
I recommend that if you have had a small bowel biopsy, that you get a copy of the pathologists report. It may state how many samples were taken. The American Gastroenterological Association recommends at least four samples are taken because that has proven to double the diagnostic rate for celiac disease.
The report may state the condition of the villi and should state something about the condition of the intraepithelial area and what kinds of white blood cells are found in this area if any at all. The picture above is of a biopsy sample viewed under the microscope, and it has a lot of white blood cells in the intraepithelial area of the broken down villi. They show up as black dots.
The following report from Stanford on Celiac disease: surgical pathological criterion, shows you how complicated it is for the pathologist to make a report and an impression which will help the treating doctor make a diagnosis.
Chronic enteritis secondary to gluten sensitivity
Gluten sensitive enteropathy
Villous atrophy in small intestine
May be variable and patchy
Most symptomatic patients have total villous atrophy
Defined as completely flattened villi
Partial atrophy more common in pre-symptomatic or post-treatment patients or in relatives being screened
Increased intraepithelial lymphocytes in small intestine may be seen with or without atrophy
Cutoff varies by location
Duodenum >30 / 100 enterocytes
Alternative proposed is 6-12 / 20 enterocytes at the tips of villi
Jejunum >40 / 100 enterocytes
Occasionally seen in stomach and large intestine
T cell phenotype
CD2+, CD3+, CD8 70-90%
Gamma delta T cell receptor
CD3 stain is useful for identification and counting
Intraepithelial lymphocytes evenly distributed from bottom to top of crypts or increased at tops
Normal distribution is decreasing from bottom to top
Villi must be well oriented to be certain that what appears to be the top is not a semi- tangentially cut section of mid-villus
Identification of an abnormal distribution or of more than rare lymphocytes on H&E is a clue that it may be worth staining and counting cells
Increased intraepithelial lymphocytes in the absence of villus atrophy is suggestive of latent or partially treated celiac disease but not specific, as it can be seen in:
Infections (Giardia, Helicobacter, Cryptosporidium, viruses)
Drug reactions (NSAIDS)
Immune system abnormalities
There is a lot of good information in the whole report here,
Of note, I disagree the the serum anti tissue transglutaminase IgG is 95% sensitive and 98% specific. Dr. J. Abram from Columbia showed that the test, when used in real life was closer to 51%-71% sensitive and 69%-100% specific.
Ensari A. Gluten-sensitive enteropathy (celiac disease): controversies in diagnosis and classification. Arch Pathol Lab Med. 2010 Jun;134(6):826-36.
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