STRX Week 3 & 4 Flashcards
Identify the organs and explain the rationale
Left: Duodenum - presence of Brunner’s glands in submucosa
Middle: Jejunum - plica circulares (extensions of submucosa)
Right: Ileum - presence of Peyer’s patches (lymphatic nodules in submucosa)
What area of the small intestinal mucosa is most susceptible to injury during an ischemic event and why?
Surface epithelium - they depend on blood capillaries in lamina propria that travel along crypts - furthest from blood source - most susceptible
What are two characteristics of ischemic intestinal disease?
Attentuation/atrophy of the surface epithelium
Normal to hyperproliferative crypts
What type of necrosis do you expect to see in the intestine following ischemia? Why?
Coagulative necrosis due to firm texture of the tissue
What is transmural infarction? When does it usually occur?
Infarction (lack of blood supply) that involves mucosa, submucosa, and muscularis propria - occurs due to acute blockage of major blood vessel
Why is mortality after ischemia higher in patients with right-sided colonic disease?
Both the small intestine and the right side of the colon are supplied by the superior mesenteric artery.
What are some causes and the result of occlusive intestinal ischemia?
What are some causes and the result of non-occlusive?
Causes of Occlusive:
1. Thrombus/embolism of superior mesenteric artery/vein
2. Systemic vasculitis of small arteries
3. Extrinsic compression of vasculature due to tumors, adhesion, strictures, strangulation, volvulus,
intussusception, herniation
4. CMV infection, which can result in localized vascular obstruction
Resulting in acute mesenteric ischemia
Non-occlusive:
1. Diabetes
2. Chronic NSAID use
Usually results in chronic mesenteric ischemia
Describe the pathogenesis of intestinal ischemia.
Loss of blood flow to the intestinal tissue results in hypoxic damage; however, most damage occurs due to reperfusion
injury when blood supply is restored; Restoration of oxygen supply results in generation of reactive oxygen species,
eicosanoids, nitric oxide, endothelin and several cytokines, resulting in vasoconstriction, inflammation, complement
activiation, and finally, tissue destruction.
What is the prognosis of instestinal ischemia, and what factors influence the prognosis?
Poor
Prognostic indicators include coexisting COPD and persistence of symptoms for more than 2 weeks. Rapid diagnosis and relief form persistent vasoconstriction are keys to improve these results. Surgical revascularization, intraarterial perfusion with a thrombolytic agent or infusion of vasodilators, and simple systemic anticoagulation are choices of therapy
The multifocal, well-circumscribed tumor growths on the small intestine and the presence of monomorphic cells with characteristic stippled (“salt and pepper”) chromatin within round nuclei suggests what type of tumor?
Neuroendocrine
What immunohistochemical stains would be used to confirm diagnosis of neuroendocrine tumor of the small intestine?
Chromogranin and Synaptophysin
What is a carcinoid syndrome? Which 2 substances are elevated in patient with classic carcinoid syndrome?
Neuroendocrine tumors release biologically active amines and peptides into blood, which escape inactivation by the liver, and cause multiple symptoms.
Serotonin (5-hydroxy tryptamine) and its metabolite, 5-hydroxy indole acetic acid (5-HIAA) are normally elevated in these patients.
Neuroendocrine tumors in what location tend to metastasize?
Which location tend to be aggressive?
NET in what location tend to be benign?
Foregut metastasize
Midgut aggressive
Hindgut benign
What factors portend a worse prognosis in GI neuroendocrine tumors
Degree of histological differentiation
Mitotic rate
Ki-67 proliferative index
Behavior is also affected by size and location
Suppose this tumor secreted gastrin, what changes would you expect to see in the stomach?
This is an example of a gastrinoma, associated with
the Zollinger-Ellison syndrome.
Gastrin would drive the proliferation of parietal cells, resulting in increased acid production.
Describe the duodenum in terms of its anatomical relationships with surrounding structures and its different named parts.
Duodenum has 4 parts: superior, descending, horizontal, ascending
Anterior to horizontal: superior mesenteric a. and v.
Posterior to horizontal: aorta and IVC
What is an anatomical landmark used to differentiate an upper versus a lower GI bleed?
What is the function of that landmark?
Ligament of Trietz
Connects the diaphragm to the duodenojejunal flexure - widens and elevates it during breathing - facilitates movement of intestinal contents
The small intestine except for [what] is considered intraperitoneal?
2nd, 3rd, and 4th parts of the duodenum are retroperitoneal
Outline the blood supply to the duodenum proximal to entry of the major duodenal papilla.
Aorta → Celiac Trunk → Common Hepatic artery → Gastroduodenal artery → SUPERIOR Pancreaticoduodenal artery (Anterior & Posterior branches), Duodenal branches
Outline the blood supply to the duodenum distal to entry of the major duodenal papilla.
Aorta → Superior Mesenteric artery → INFERIOR Pancreaticoduodenal arteries (Anterior & Posterior branches)
How would a pt feel epigastric pain from the duodenum?
Via the sympathetic pathways
Periarterial* → Celiac or Superior Mesenteric Ganglia → Greater/Lesser Splanchnic Nerve → Paravertebral Ganglion → White Communicating Rami → Anterior Primary Rami → Spinal nerve → Dorsal Root → Cell bodies in Dorsal Root Ganglion → Dorsal Root → Dorsal Rootlets → Dorsal Horn (location of Synapse)
Periaterials:
Gastroduodenal artery → Superior Pancreaticoduodenal artery
Superior Mesenteric artery → Inferior Pancreaticoduodenal arteries
What is the structure and function of the mesentery?
fan-shaped fold of peritoneum that attaches the jejunum and ilium to the posterior abdominal wall
The jejunum has [longer/shorter] vasa recta as compared to the ileum?
Longer
How would a spinal cord injury at T8-10 affect the small intestine?
Loss of sympathetic innervation to the jejunum and ileum –> increased peristalsis and blood flow
Parasympathetics not affected bc it’s recieved from vagus n
Color: Red — Pink
Wall: Thicker — Thinner
Vascularity: Greater — Less
Vasa recta: Longer — shorter
Arterial arcades: Larger and fewer — smaller and more
Fat in mesentery: Less, pale — more, encroaching
Plicae circulares: Prominent — Sparse
Characterize Primary Biliary Cholangitis and outline expected laboratory findings
Autoimmunity and inflammation of extrahepatic bile ducts leading to cholestasis and biliary fibrosis
Predominately in females
Florid duct lesions
Associated with sjogren syndrome and thyroid disease
Expected labs:
Elevated bilirubin, ALP, GGT (cholestatis pattern)
Positive Antimitochondrial antibodies
A pt’s labs show positive AMA and the following histologic findings:
What is the likely diagnosis? Interpret the histological findings
Primary Biliary Cirrhosis (PBC)
Destruction of bile duct
Characterize Primary Sclerosing Cholangitis and outline expected laboratory findings
Autoimmune disease with progressive inflammatory and sclerosing destruction of intrahepatic and extrahepatic bile ducts
Predominately male
Associated with IBD and Pancreatitis
Fibrotic Duct Obliteration with strictures and beading on biliary imaging
Unpredictable clinical course
Expected labs:
Elevated bilirubin, ALP, GGT (cholestatis pattern)
Elevated assay for pANCA
Negative AMA
A pt’s labs show negative AMA, elevated pANCA and the following histologic findings:
Primary Sclerosing Cholangitis (PSC)
Onion skin lesion, tombstone scar
Characterize Autoimmune hepatitis and outline expected laboratory findings
Autoimmune disorder of antibodies attacking hepatocytes
Predominately females
Associated with Lupus, rapidly progressive
Normal biliary imaging with plasma cell-rich infiltrates and Regenerative Rosettes on biospy
Most likely to present in fulminant failure
Expected labs:
Dramatically elevated AST, ALT (hepatocellular pattern)
Positive ANA, Anti-smooth muscle Abs with elevated serum IgG
A pt’s labs show elevated AST/ALT, positive ANA, and elevated serum IgG, and the following histologic findings:
Autoimmune hepatitis
Plasma cell infiltrates, Regenerative Rosettes
After SER, where do triglyceride droplets migrate to?
What happens in those organelles?
RER then Golgi
Assembling of chylomicrons
What cells are seen in the crypt of small intestine?
Enterocytes
Goblet cells
Paneth cells
Enteroendocrine cells
What is the function of paneth cells? What do they secrete?
Host defense against microbes by secreting antimicrobail peptides and proteins into lumen of the crypt
Secrete defensins, lysozymes and PLPA2
List the enteroendochrine cells of the small intestine.
S cells - secretin
I cells - CCK
+ 4 others
What is the relationship between intestinal M cells and HEVs?
M cells are cells in the ileum without microvilli that are located at the apical edge of Peyer’s Patches
M cells are antigen presenting cells but have no lymphocyte properties in itself, so HEVs would be present near M cells T cells to travel to lymph node after activation
What are Peyer’s patches? Where are they located?
Located in the submucosa of the ileum - they are lymphoid aggregates that form large follicles
What are Brunner’s glands? Where are they located?
Mucus-secreting glands in the submucosa of the duodenum, drain mucus into the crypts
Does this CT have contrast?
What is the abnormality?
Yes
Cirrhosis:
Ascites in the abdomen
Small, scalloped liver
Splenomegaly
Explain the following 3-phase image series
Top left is no contrast
Top right is arterial (contrast in aorta)
Bottom left is portal-venous (contrast getting into portal vein lighting up liver)
Bottom right is delayed contrast
Interpret this ultrasound
Simple cyst in the liver
Well-circumscribed, hypoechoic, enhanced brightness in shadow area
Interpret the CT
Small Bowel Follow Through/ Barium
Irregularly thickened small bowel mucosal folds
How would you differentiate the pancreas from the parotid gland?
Presence of islets of Langerhans
Absence of striated ducts
Label the following:
Acinar cells
Centroacinar cells
Intercalated ducts
Identify the Islets of Langerhans
Explain the functions of the duct system in the pancreas
The acinar cells synthesize and release digestive enzymes into intercalated ducts (lined proximally by centoacinar cells) –> join to form intralobular ducts —> merge to form interlobular ducts –> secretions finally reach the main pancreatic duct of Wirsung or the accessory pancreatic duct of Santorini.
Epithelial cells lining the intercalated ducts produce a bicarbonate and sodium-rich alkaline pH fluid which dilute zymogens secreted by acinar cells. The other pancreatic ducts do not contribute as much fluid as the intercalated ducts.
Submucosal (Brunner) glands in the proximal part of the duodenum also secrete an alkaline fluid that helps to neutralize the acidity of gastric juice.
How is the pancreas protected from autodigestion by the acid hydrolytic enzymes?
The enzymes are secreted as zygomens
Co-packaging of trypsin inhibitor with trypsinogen prevents the premature activation of trypsin
Optimal pH for pancreatic enzyme activity is only after in the duodenum
Which enzymes are primarily involved in catalyzing the conversion of pancreatic zymogens to active enzymes within the duodenum?
Enteropeptidase converts trypsinogen to trypsin
Trypsin then activates the other proenzymes
[a] stimulates enzyme secretion by acinar cells
[b] promotes water and bicarb secretion by ductal cells
a. CCK
b. Secretin
CCK stimulates enzyme secretion by [a] cells
Secretin promotes water and bicarb secretion by [b] cells
a. acinar
b. ductal
What layers are missing from the epithelium of the gallbladder?
No muscularis mucosa or submucosa
Does the gallbladder have adentitia or serosa?
Adventitia where it attaches to liver
Serosa elsewhere
What is the encircled stricture?
What’s a possible outcome of it?
Rokitansky-Aschoff sinus
Invagination of mucous membrane into muscularis externa due to hyperplasia of epithelial cells through fibromuscular layer of gallbladder wall
Risk factor for formaiton of pigmented gallstones
What is the most likely precursor to Pancreatic carcinoma?
Pancreatic Intraepithelial Neoplasia
Female predominance
Doesn’t involve duct system
Almost always benign
Most commonly seen in tail of pancreas
Serous Cystic Neoplasm
Female predominance
Doesn’t involve duct system
May be premalignant
Most commonly seen in tail of pancreas
Associated with “ovarian-type” stroma
Mucinous Cystic Neoplasm
Male predominance
Arises in duct system
May be premalignant
Most commonly seen in tail of pancreas
Intraductal Papillary Mucinous Neoplasm (IPMN)
Identify the tumor type for each picture and explain why
Pink: HCC tumor - cells that look like hepatocytes but have no portal tracts and thin trabeculae
Purple: adenocarcinoma - fibrotic tissue forming abnormal ducts or glands
What are the risk factors of HCC?
Hepatitis
EBV
AFLA - found in wheat/corn
Aspergillus
Any liver disease that can cause chronic inflammation and repair
What are the two most common molecular/genetic alterations
associated with development of hepatocellular carcinoma?
Activation of β-catenin and inactivation of p53
What entities are considered potential precursor lesions to HCC?
Hepatocellular adenoma, small cell change, large cell change (in some HBV infections), high-grade dysplastic nodule
What liver lesion is associated with anabolic steroid use?
Hepatic adenoma - benign proliferation of hepatocytes - sometimes increased risk of HCC
Under what circumstance is hepatic adenoma considered a premalignant lesion?
β-catenin mutation
What’s the difference between these two images?
Left: Enteric contrast
Right: Enteric and IV contrast
Liver flukes are associated with what lab finding?
elevated CA19-9
What’s the major clinical concern for liver flukes?
Can lead to adenocarcinoma
Imaging modality, body region, abnormality
MRCP - Magentic Resonance Cholangiopancreatography
Angiogram of liver without contrast
Cholangiocarcinoma
What structures divide the peritoneal cavity into compartments?
Transverse mesocolon
What are the boundaries of the lesser sac and greater omental foramen?
Hepatoduodenal Ligament (Ant)
IVC (Post)
Liver (Sup)
Duodenum - 1st part (Inf)
List the pathway of visceral pain from the right lobe of the liver back to the spinal cord
Right lobe of liver –> R Hepatic a. –> Proper Hepatic a. –> Common Hepatic a. –> Celiac trunk –> Greater Splanchnic n. –> White Ramus Communicans –> Sympathetic chain ganglion –> primary ramus –> spinal nerve –> dorsal root –> dorsal root ganglion –> dorsal root –> dorsal rootlets –> dorsal horn
What relationships can you use to find the cystic artery?
Finding the Proper hepatic a and right hepatic a
The liver is a major producer of lymph. Generally, lymph drainage of the liver and gallbladder follow one of two major routes. What are these two routes?
Superficial lymphatics from anterior aspect of visceral surfaces –> hepatic lymph nodes –> celiac LN –> cisterna chyli
Superficial lymphatics from posterior aspect –> phrenic LN or deep lymphatics –> post mediastinal LN –> R lymphatic duct or thoracic duct
What branch of the celiac trunk crosses anterior to the tail of the pancreas?
Splenic a
Map the arterial flow for the body and tail of the pancreas from the abdominal aorta.
Arterial arcade - Head and neck: Celiac trunk –> common hepatic a. –> gastroduodenal a. –> anterior/posterior superior pancreaticoduodenal a.
SMA –> anterior/posterior inferior pancreaticoduodenal a.
Body: celiac trunk –> splenic a. –> dorsal pancreatic a. (artery anastomoses with a. supplying head & neck, artery can arise from celiac trunk or common hepatic a. *usually given off of splenic close to origin of splenic a from celiac trunk
Middle Body: celiac trunk –> splenic a. –> great pancreatic a
Tail: celiac trunk –> splenic a. –> caudal pancreatic a/arteries to the tail
Map the venous flow for the subdivisions of the pancreas to the hepatic portal vein.
Anterior/posterior superior/inferior pancreaticoduodenal veins from head and neck –> SMV –> portal vein
Pancreatic vein from tail and body –> splenic vein –> portal vein
What structure marks the transition from foregut to midgut?
Main pancreatic duct
What abdominal organ does pancreatic cancer typically metastasize to and why?
Liver - hepatic portal vein forms posterior to the neck of the pancreas
What radiation type and source are employed in a Radionuclide Cholescintigram (HIDA scan)
Gamma (ionizing)/ TC99-m Choletec through IV
What are the imaging modality and body
parts depicted?
Endoscopic retrograde cholangiopancreatogram (ERCP)
How would congestive heart failure effect the liver?
Cause hepatomegaly from an increase in central venous pressure leading to blood engorgment
Relate cirrhosis to ascites
Obstruction to blood flow in the liver and deficiency in albuimin can result in portal hypertension –> increased hydrostatic pressure in portal vein and intrahepatic branches and decrease osmotic pressure from reduction of plasma albumin –> fluid accumulation in peritoneal cavity –> ascites
Explain the zones of the Liver acinus
Zone I - central venous drainage - region where oxygen concentration is poorest - hepatocytes susceptible to damage by hypoxia
Zone II - intermediate region
Zone III - periportal - heptocytes actively synthesize glycogen and plasma proteins - oxygen concentration is high
What surface of the hepatocyte is against the bile canaliculi?
What surface is against the Space of Disse?
Surface against bile canaliculi - apical
Space of Disse - basal
Outline the flow of Bile
Biliary canaliculi –> Canal of Hering –> Intrahepatic Bile Duct –> Interlobular Bile Duct –> R and L Hepatic Ducts –> Common Hepatic Duct –> Common bile duct
