Gastrointestinal Pathology- Small bowel Flashcards
You are seeing a new born in the hospital who has the main complaint of bilious vomiting. On PE, his stomach appears distended. Images on XRAY show the presence of two large circles that look like bubbles. What could be causing this presentation? What other disease is this associated with? What are some other clinical features and what is causing the “double bubble” sign?
He has duodenal atresia which is a congenital failure of duodenum to canalize. It is associated with Down syndrome. Other clinical features are polyhydraminos. The double bubble sign is from the blind loop of duodenum.
You are looking at a pathology specimen and it looks like a portion of bowel where all three layers of the bowel wall are out-pouching. What is this called and what causes it? How many people in the population are with this disease? How long is it? Where is it located and how far is it from the ileocecal valve?
This is Meckel Diverticulum which arises due to failure of the vitelline duct to involute. Follows the rule of 2s. 2% of the population, 2 inches long, 2 feet of the ileocecal valve
Is Meckel Diverticulum a true or a false diverticulum? How can it present during the first two years of life?
Yes, it is a true diverticulum. It can present with bleeding, volvulus, intussusception or obstruction. However most cases are asymptomatic.
What is a volvulus? what does it result in and what are the most common locations in elderly and children?
Twisting of bowel along its mesentery. Results in obstruction and disruption of the blood supply with infarction. Most common locations are sigmoid colon (in elderly) and cecum (young adults).
What is intussusception and what does what does it lead to? What is the most common cause in children and which location is it mostly present? What organism is responsible? What is the cause of it in adults?
Telescoping of proximal segment of bowel forward into the distal segment. Telescoped segment is pulled forward by peristalsis, resulting in obstruction and disruption of blood supply with infarction.
In children, most common cause is lymphoid hyperplasia due to ROTAVIRUS. Usually arises in the terminal ileum, leading to intussusception into the cecum. In adults , most common cause is tumor.
A patient comes to your clinic with complaints of abdominal pain and bloody diarrhea. When auscultating his abdomen, you notice that the bowel sounds seem decreased. What could be causing this presentation? What two processes are involved that can damage the bowel?
He has a small bowel infarction.
- Transmural infarction that occurs with thrombosis/embolism of the superior mesenteric artery or thrombosis of the mesenteric vein.
- Mucosal infarction occurs with marked hypotension.
A 16 year old teenager presents to your clinic with complaints of abdominal distention and diarrhea upon consumption of milk products. What could he have and what anatomical structures are involved? How did he get this disease?
He has lactose intolerance due to decreased function of the lactase enzyme found in the brush border of enterocytes. Deficiency may be congenital (autosomal recessive) or acquired (often develops in late childhood. Temporary deficiency is seen after small bowel infection.
What is celiac disease? Which HLAs is it associated with? How is it managed? What are some complications it may cause?
Immune-mediated damage of small bowel villi due to gluten exposure. Associated with HLA-DQ2 and DQ8. Symptoms resolve with gluten free diet. Small bowel carcinoma and T-cell lymphoma are late complications that present as refractory disease despite good dietary control.
Where is gluten found and How does gluten cause the damage in Celiac disease?
Gluten is found in wheat and grains and its most pathogenic form is gliadin. Once absorbed, gliadin is deaminated by tissue trans glutaminase (tTG). Deaminated gliadin is presented by antigen presenting cells via MHC class II. Helper T cells mediate tissue damage.
What are laboratory findings in celiac disease? What are biopsy findings?
- IgA antibodies against endomysium, tTG, or gliadin; IgG antibodies are also present and are useful for diagnosis in individuals with IgA deficiency.
- Duodenal biopsy reveals flattening of villi, hyperplasia of crypts and increased intraepithelial lymphocytes. Damage is most prominent in the DUODENUM.
If a child comes to the peds clinic with abdominal distention, diarrhea and failure to thrive what is on your differential?
CELIAC disease
If an adult presents with chronic diarrhea and bloating, what is on your differential?
CELIAC disease
What skin findings are on patients with celiac disease and how are they managed?
Small, herpes like vesicles may arise on skin (dermatitis herpetiformis). Due to IgA deposition at the tips of dermal papillae, resolves with gluten-free diet.
What is the difference between tropical sprue and celiac disease?
Tropical sprue occurs in tropical regions, arises after infectious diarrhea and responds to antibiotics. Damage is most prominent in jejunum and ileum and can lead to secondary vitamin B12 or folate deficiency, unlike CELIAC which targets DUODENUM.
What is whipple disease and what would you see on histology? How does this disease occur?
Systemic tissue damage characterized by macrophages loaded with Tropheryma whippelii organisms. Partially destroyed organisms are present in macrophage lysosomes. Macrophages compress lacteals in small bowel lamina propria which prevents chylomicrons from being transferred from enterocytes to lymphatics. Results in fat malabsorption and steatorrhea.
What is the most classical site of Whipple disease and what are other sited of involvement?
Classic site is the small bowel lamina propria. Other common sites include synovium of joints (arthritis), cardiac valves, lymph nodes and CNS.
A patient presents with malabsorption. Lab work shows that this guy has no VLDL and no LDL. What does he have and why does he have these findings?
He has Abetalipoproteinemia which is an autosomal recessive deficiency of apolipoprotein B-48 and B-100. Malabsorption is due to defective chylomicron formation (which requires B-48) and absent plasma VLDL and LDL which require B-100.
