Flashcards in CH10 - Gastrointestinal Pathology Deck (345)
How does lactose deficiency develop?
it may be congenital (rare autosomal recessive disorder) or acquired (often develops in late childhood);
How is lactose deficiency related to small bowel infarction?
temporary deficiency is seen after small bowel infection (lactase is highly susceptible to injury).
What is celiac disease?
Immune-mediated damage of small bowel villi due to gluten exposure
What is celiac disease associated with?
HLA-DQ2 and DQ8
In what is gluten present?
in wheat and grains
What is the most pathogenic component of gluten?
What happens to gliadin once absorbed?
gliadin is deamidated by tissue transglutaminase (tTG).
What happens to deamidated gliadin?
it is presented by antigen presenting cells via MHC class II where the helper T cells mediate tissue damage.
What is the clinical presentation for celiac disease in herpes?
Children classically present with abdominal distension, diarrhea, and failure to thrive
What is the clinical presentation for celiac disease in adults?
It classically presents with chronic diarrhea and bloating
What is seen on the skin in celiac disease?
Small, herpes-like vesicles may arise on skin (dermatitis herpetiformis).
What is dermatitis herpetiformis in celiac diseae due to and how does it resolve?
IgA deposition at the lips of dermal papillae it resolves with gluten-free diet
What are the laboratory findings for celiac disease?
1) IgA antibodies against endomysium, tTG (tissue transglutaminase), or gliadin
What lab finding for celiac disease is also used in IgA deficiency?
IgG antibodies are also present and are useful for diagnosis in individuals with IgA deficiency
What is the relationship between IgA deficiency and celiac disease?
increased incidence of IgA deficiency is seen in celiac disease
What does duodenal biopsy reveal in celiac disease?
flattening of villi, hyperplasia of crypts, and increased intraepithelial lymphocyte
In celiac disease where is damage most prominent?
in the duodenum (jejunum and ileum are less involved)
When would the symptoms of celiac disease resolve?
with gluten-free diet.
What are late complications that present as refractory disease despite good dietary control?
Small bowel carcinoma and T-cell lymphoma
What is tropical sprue?
Damage to small bowel villi due to an unknown organism resulting in malabsorption
How does tropical spure compare to celiac disease?
Its similar to celiac disease except 1. Occurs in tropical regions (e.g., Caribbean) 2. Arises after infectious diarrhea and responds to antibiotics
In tropical spure, where is damage most prominent?
in jejunum and ileum (secondary vitamin B12 or folate deficiency may ensue); duodenum is less commonly involved.
What is whipple disease?
Systemic tissue damage characterized by macrophages loaded with Tropheryma whippelii organisms; partially destroyed organisms are present in macrophage lysosomes (positive for PAS).
What is the classic site of involvement in whipple disease?
the small bowel lamina propria
What happens in whipple disease?
1. Macrophages compress lacteals. 2. Chylomicrons cannot be transferred from enterocytes to lymphatics. 3. Results in fat malabsorption and steatorrhea
What are the other common sites of involvement for whipple disease?
they include synovium of joints (arthritis), cardiac valves, lymph nodes, and CNS.
What is abetalipoproteinemia?
Autosomal recessive deficiency of apolipoprotein B-48 and B-100
What are the clinical features for abetalipoproteinemia?
Malabsorption due to defective chylomicron formation (requires B-48), Absent plasma VLDL and LDL (requires B-100)
What is carcinoid tumor?
Malignant proliferation of neuroendocrine cells; low-grade malignancy