GI malabsorption morphologies

Question 1

1. Which biopsy speciments are generally diagnostic in celiac disease?
2. What characterizes the histopathology of ceiliac disease?
3. What causes the malabsorption seen in celiac disease?
4. What is a sensitive marker of celiac disease, and how specific is it?
5. What is the greatest diagnostic criteria?

Answer 1

1. Biopsy specimens from 2nd portion of the duodenum or proximal jejunum generally diagnostic in CD: they are exposed to the highest concentrations of dietary gluten
2. histopathology characterized by
   
   1. villous atrophy
   2. increased numbers of intraepithelial CD8+ T lymphocytes (intraepithelial lymphocytosis)
   3. crypt hyperplasia
3. loss of mucosal + brush-border surface area probably accounts for the malabsorption.
4. increased rates of epithelial turnover–> increased crypt mitotic activity
   
   1. may limit ability of absorptive enterocytes to fully differentiate or proteins necessary for terminal digestion + transepithelial transport.
5. an increase in the number of intraepithelial lymphocytes, particularly within the villus, is a sensitive marker of celiac disease
6. intraepithelial lymphocytosis and villous atrophy are not specific for celiac disease: can be present in other diseases, including viral enteritis.
7. The combination of histology and serology, therefore, is most specific for diagnosis of celiac disease.

Question 2

what changes in the lamina propria do we see in CD?

Answer 2

fully developed celiac disease includes increased numbers of

1. plasma cells
2. mast cells
3. eosinophils

especially within the upper part of the lamina propria.

Question 3

1. silent celiac disease
2. latent celiac disease

Answer 3

silent celiac disease: defined as positive serology and villous atrophy without symptoms

latent celiac disease: positive serology is not accompanied by villous atrophy

Question 4

Congenital lactase deficiency , caused by a mutation in the gene encoding lactase, is an autosomal recessive disorder. The disease is rare and presents as explosive diarrhea with watery, frothy stools and abdominal distention upon milk ingestion. Symptoms abate when exposure to milk and milk products is terminated, thus removing the osmotically active but unabsorbable lactose from the lumen. As a result, congenital lactase deficiency was often fatal prior to the availability of soy-based infant formula.

•

Acquired lactase deficiency is caused by down-regulation of lactase gene expression and is particularly common among Native American, African American, and Chinese populations. Acquired lactase deficiency can develop following enteric viral or bacterial infections and may resolve over time. Symptoms of acquired lactase deficiency, including abdominal fullness, diarrhea, and flatulence, due to fermentation of the unabsorbed sugars by colonic bacteria, are triggered by ingestion of lactose-containing dairy products.

Answer 4

1. an autosomal recessive disorder.
2. disease is rare and presents as explosive diarrhea with watery, frothy stools and abdominal distention upon milk ingestion.
3. congenital lactase deficiency was often fatal prior to the availability of soy-based infant formula.
   4.