Pathology-Lower GI Flashcards
What events make up 80% of mechanical GI obstructions? What makes up the other 20%?
Herniation, adhesions, volvulus and intussusception. Perforation, tumor and ischemia make up the other 20%.
What type of blood vessels get backed up 1st in a volvulus?
Veins, they are lower pressure.
In what demographic is this GI obstruction common in?
Kids. Their mesentery is looser than adults. A leading edge (Meckel’s diverticulum, polyp or cancer) causes tunneling of one portion of the intestine into another portion.
What are risks of the condition seen below?
Hernias can be strangulated or incarcerated (entrapped, gets stuck in the space).
What portion of the bowel is most sensitive to ischemic events?
Mucosa in watershed areas (where SMA and IMA meet)
Why are older patients typically the ones presenting with an ischemic bowel?
Common causes are hypo perfusion from atherosclerosis, which takes years to develop.
What is a large risk factor for the condition shown below?
This is ischemic bowel. Damage to the mucosa allows bacteria to enter the blood stream.
When do you see chronic bowel ischemia in younger people?
Runners, IBD and bowel damage causing ischemia due to fibrosis.
A 77 year old man presents with a superior mesenteric artery thrombosis. What would you expect histology of his small intestine to look like?
Upper portion of mucosa is necrotic and deeper portion of glands near muscularis mucosa is preserved.
3 diseases most commonly responsible for malabsorption?
Pancreatic insufficiency, celiac disease and Crohn disease.
4 categories of diarrhea
Secretory, osmotic, malabsorption and exudative
What increases your genetic susceptibility for celiac disease?
HLA DQ2 or DQ8
You are doing an endoscopy on a patient’s duodenum who has been losing weight and experiences diarrhea after ingestion of gluten products. What would you expect to see on histological examination of this tissue?
This patient has Celiac disease, you can tell by the gross villous atrophy. On histological examination you would see villous atrophy, crypt hyperplasia and intraepithelial lymphocytes. Note how small the crypts are in the normal patient.
You are doing an endoscopy on a patient’s duodenum who has been losing weight and experiences diarrhea after ingestion of gluten products. What cancers is this patient at risk for?
T-cell lymphoma and adenocarcinoma.
How does intestinal tissue differ from stomach tissue?
In the stomach, goblet cells and lymphocytes mean chronic gastritis. These are present normally in the intestine.
2 most common diseases in inflammatory bowel disease.
Ulcerative colitis and Crohn disease. 10% of people will not be diagnosed by biopsy.
How does location of ulcerative colitis differ from Crohn disease?
Crohn disease has skip lesions and is most often found in the distal ileum and colon. Inflammation is transmural with fissures and ulcerations all the way out to the serosa with thickening of the walls. Ulcerative colitis is continuous from the rectum to the colon. Inflammation is superficial and the wall is thinned.
A 21 year old man presents with episodic diarrhea and abdominal pain. Endoscopy is done and he is diagnosed with Crohn disease. What would you see histologically?
Deep ulcerations and fissures, superficial inflammation and inflammatory nodules all the way out to the serosa. Granulomas are also characteristic of this disease, but rarely seen.
A 21 year old man presents with episodic diarrhea and abdominal pain. 2 days later he dies in an automobile accident and autopsy of his bowel is shown below. What is your diagnosis?
He has rake ulcers (railroad tracks), creeping fat and cobblestoning of the mucosa. These are typical in Crohn disease.
A 21 year old man presents with episodic diarrhea and abdominal pain. Why might he have a lot of trouble passing stool if you diagnose him with Crohn disease?
Chronic inflammation from Crohn disease can cause fibrosis and stenosis of the bowel lumen.
A 21 year old man presents with episodic diarrhea and abdominal pain. Endoscopy is done and he is diagnosed with Crohn disease. What are complications of his disease?
Fistula formation (shown below), adhesions, hemorrhage, obstruction, abscesses. Systemic symptoms also include the joints, eyes, liver and skin.
A 17 year old man presents with episodic abdominal pain and diarrhea. After endoscopy, you diagnose him with ulcerative colitis. What would you expect to see on histological examination of the affected tissue?
Superficial ulcerations, inflammation (crypt abscesses and crypitis) and longitudinal burrowing beneath the mucosa forming pseudopolyps.
What complication of ulcerative colitis is very rare in Crohn’s disease? What increases your risk for this complication in ulcerative colitis?
Cancer. Ulcerative colitis is precancerous. Increased risk factor for cancer are: duration, length of bowel involved, severity of inflammation, primary sclerosing cholangitis and family history of colon cancer.
What is your diagnosis in this patient with IBD?
Ulcerative colitis, note how the affected area is continuous.
Compare and contrast these aspects of Crohn disease and ulcerative colitis:
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A 76 year old woman presents with lower left quadrant abdominal pain and cramping. She has a long history of constipation. Endoscopy is shown below. What complications is she at risk for?
She has diverticular disease, probably from eating a Western diet and being constipated which increases luminal pressure and causes muscle hypertrophy. Typically these are asymptomatic, but can present with inflammation (diverticulitis), fistulae, perforation or hemorrhage.
What would you expect to see on histological examination of this patient’s sigmoid colon?
Diverticula happen as a result of muscularis externa hypertrophy which is shown below. The mucosa then out pouches through the muscle as seen below.
Where are these most commonly found?
Intestinal polyps are most common found in the colon.
What polyp syndromes are these types of polyps associated with: benign, neoplastic, hamartoma and inflammatory?
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A 15 year old girl presents with skin macules and fecal occult blood. Endoscopy reveals arborizing polyps in the small intestine, colon and stomach. What genetic mutation is her condition associated with and what complications is she at risk for?
Peutz-Jeghers syndrome is associated with the gene LKB1/STK11. She is at risk for colonic adenocarcinoma and cancer of the thyroid, breast, lung, pancreas, gonads and bladder. Note the “raspberry-like” polyp.
A patient comes in for his annual colonoscopy. A polyp is biopsied and histology is shown below. What is your diagnosis?
Note that it is sessile. Note that goblet cells become hyper plastic. This is a hyper plastic benign polyp.
A 15 year old boy presents with abdominal pain. CT reveals intussusception. After surgery, he is diagnosed with Peutz-Jeghers syndrome. What was causing his intussusception and what would histology look like?
He had a hamartomatous polyp causing the intussusception. Histology would show elongations of muscular fibers through the polyp
What are the different subtypes of adenomatous polyps?
Tubular, villous and tubulovillous.
Why are villous adenomas more difficult to treat when cancerous than tubular adenomas?
Tubular adenomas grow with a stalk. If the adenocarcinoma is at the top of the stalk, clipping it off will cure the patient. Villous adenocarcionmas have no stalk and can invade deeper to the muscular layer.
What would you expect to see on histology of tubular adenoma?
Glandular, pedunculated, precancerous polyps. It is precancerous so you will see increased nucleus to cytoplasm ratio, dysplatic nuclei etc.
What would you expect to see on histology of villous adenoma?
Finger-like projections, sessile, larger than tubular adenoma and difficult to resect.
Which part of this colon has a tubular adenoma and which has a villous adenoma? Which is more common?
Tubular adenomas are much more common, which is shown on the right. Villous adenoma is on the left.
A 55 year old man presents with painless rectal bleeding. Endoscopic biopsy reveals colorectal carcinoma. What is the most common way this cancer develops?
Adenoma carcinoma sequence: 1) Double-hit mutation of APC at chromosome 5q21 2) Mutation of K-RAS at chromosome 12p12 allows for adenoma formation 3) Loss of tumor suppressor genes (p53 at 17p13, LOH at 18q21, SMAD 2 and over expression of COX-2 causes carcinoma
A 15 year old boy presents with painless rectal bleeding. Endoscopic biopsy reveals thousands of adenomatous polyps. His biopsy is shown below. What is causing his condition?
He has familial adenomatous polyposis, a result of APC/WNT pathway mutation which is autosomal dominant.
How do left sided colorectal carcinomas typically present?
They are usually a “napkin-ring” lesion. This causes obstruction, constipation, decreased stool caliber and bleeding.
What would you expect to see on histological examination of this tumor?
Colorectal carcinoma typically shows dysplastic columnar cells, dirty necrosis (debris within glands) and invasive glands with desmoplastic response (collagen matrix around infiltrating glands w/pointed edges).
How do you stage colorectal carcinoma?
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What type of carcinoma is this?
Rectal carcinoma. It is typically associated with HPV and is a squamous cell carcinoma.
This biopsy was taken from an infiltrating mass in a patient’s abdomen. What is the prognosis?
Very poor. This is mutinous adenocarcinoma, note the “sea of mucin”.
What is the most common pathogenesis of this condition seen mostly in young adults?
This is appendicitis, it is most commonly caused by lumenal obstruction, followed by infection.
