USMLE - GI Flashcards Part 9

Noncaseating granulomas and lympohid aggregates (Th1 mediated)

Strictures, fistulas, perianal disease, malabsorption, nutritional depletion, colorectal cancer

Diarrhea (w/ or w/o blood)

"Just got crushed by a stone --> red eyes, mouth hurts, and an aching back"

Migratory polyarthritis, erythema nodosum, ankylosing spondylitis, uveitis, kidney stones (Uric Acid from dehydration and CaOxylate from acidic urine), aphthous ulcers

Corticosteroids, azathioprine, methotrexate, infiximab, adalimumab

"Fat Granny, and old Crone Skipping down the Cobblestone road away from the Rec"

Autoimmune (Th2 mediated)

Colon; always rectal involvement

Continuous lesion

Friable mucosal pseudopolyps with freely hanging mesentery; Loss of haustra --> "lead pipe appearance"

Mucosal and submucosal inflammation only, crypt abscesses and ulcers, bleeding, no granulomas (Th2 mediated)

Malnutrition, sclerosing cholangitis, toxic megacolon, colorectal carcinoma (worse with right sided colitis or pancolitis)

Bloody diarrhea

Pyoderma gangrenosum, Primary sclerosing cholangitis, ankylosing spondylitis, uveitis

ASA preparation (sulfasalazine), 6-mercaptopurine, infliximab, colectomy

Recurrent abdominal pain with ≥2 of:

Pain improves with defecation

Change in stool frequency

Change in appearance of stool

No structural changes

Most common in middle aged women

Chronic timeline

May present with diarrhea, constipation or alternating

Multifaceted pathophysiology

Treat the symptoms

Acute inflammation of the appendix

Obstruction by fecalith (adults) or lymphoid hyperplasia (children)

Initial diffuse periumbilical pain migrates to McBurney's point. Nausea. Fever.

If perforates --> peritonitis

DDx: Diverticulitis (elderly), ectopic pregnancy,

Treatment: appendectomy

1/3 the distance from ASIS to umbilicus

Blind pouch protruding from alimentary tract that communicates with lumen of the gut

Most (esophagus, stomach, duodenum, colon) are acquired and are false (lack or have attenuated muscularis externa)

Occurs most often in sigmoid colon

Many false diverticula

Common (~50% in pts >60)

Caused by Increased intraluminal pressure and focal weakness in colonic wall

Associated with low fiber diet

Most often located in sigmoid colon

All 3 gut wall layers outpouch

| Meckels

Pseudodiverticulum

Only mucosa and submucosa outpouch

Occur especially where vasa recta perforate muscularis externa

Often asymptomatic or associated with vague discomfort

Common cause of hematochezia

Can lead to diverticulitis and fistula

Inflammation of diverticula LLQ pain, fever, leukocytosis, Stool occult blood +/- hematochezia May lead to colovesical fistula which would cause pneumaturia Perforation --> peritonitis, abscess formation, or bowel stenosis Treat with antibiotics

False diverticulum At Killian's Triangle Halitosis (due to trapped food particles), dysphagia, obstruction

Between Thyropharyngeal and Cricopharyngeal parts of the inferior pharyngeal constrictor

"5 2s: 2in long, 2ft from ileocecal valve, 2% of pop, First 2 years of life, 2 types of tissue" True diverticulum Caused by persistence of the vitelline duct May contain ectopic acid-secreting gastric mucosa +/or pancreatic tissue Most common congenital anomaly of the GI tract Melena, RLQ pain Can cause intussusception, volvulus or obstruction near terminal ileum Pertechnetate study for ectopic uptake

Cystic dilation of the vitelline duct

Telescoping of 1 bowel segment into distal segment Commonly at ileocecal junction Currant jelly stools Can compromise blood supply Unusual in adults (intraluminal mass or tumor). Majority in children (idiopathic, adenovirus) abdominal emergency in children

Twisting of portion of bowel around its mesentery Can lead to obstruction and infarction May occur at cecum and sigmoid colon (redundant mesentery) Usually in elderly pt

Congenital megacolon

Failure of neural crest cells --> lack of ganglion cells/enteric nervous plexus (Auerback's + Meissner's)

Chronic constipation in early life. Failure to pass meconium

Grossly dilated portion of the colon proximal to the aganglionic segment, resulting in a transition zone

Involves rectum

Risk Increases with Down Syndrome

Diagnosed with suction biopsy

Treatment: resection

Inferior: External Iliac Artery

Superior: Internal Thoracic Artery

Seen in CF

| Meconium plug obstructs intestine preventing passage of stool at birth

Necrosis of intestinal mucosa

Risk of perforation

Usually in colon but can involve entire tract

Neonates, more common in preemies

Reduction in intestinal blood flow --> ischemia

Pain out of proportion with physical findings. Pain after eating --> wt loss

Splenic flexure and distal colon

Elderly

Fibrous band of scar tissue

Commonly forms after surgery

Most common cause of small bowel obstruction

Well demarcated necrotic zones

Tortuous dilation of vessels

Hematochezia

Terminal ileum, Cecum, Ascending Colon

Older pt.

Confirmed by angiography

Masses protruding into gut lumen

90% are non-neoplastic

Sawtooth appearance

Tubular Adenoma: Small, rounded, more likely to be benign

Villous Adenoma: Long, finger like projections

Precancerous polyps that are precursors to Colorectal cancer

Malignant risk associated with increased size, villous histology (villous = villainous), increased epithelial dysplasia

Often asymptomatic. Lower GI bleed, partial obstruction, secretory diarrhea

Most common non-neoplastic polyp in colon

| Most (>50%) are in rectosigmoid colon

Sporadic lesion

Children <5

80% in rectum

Single: no malignant potential

Multiple: Increased risk for adenocarcinoma

Autosomal Dominant syndrome

Multiple non malignant harmatomas throughout GI tract

Hyperpigmented mouth, lips, hands and genitalia

Increased risk for colorectal cancer and other visceral malignancies

3rd most common cancer; 3rd most deadly

Most pts are >50

~25% have family history

Familial Adenomatuous Polyposis (FAP)

Gardner's Syndrome

Turcot's Syndrome

Hereditary Nonpolyposis Colorectal Cancer (Lynch Syndrome)

Autosomal dominant

Mutation of APC gene on chromosome 5q (2 hit hypothesis)

100% progress to CRC

Thousands of polyps; Pancolonic

Always involves rectum

FAP + Osseous and soft tissue tumors, congenital hypertrophy of retinal pigment epithelium

"Turcot = Turban"

| FAP + malignant CNS tumors

Autosomal Dominant

Mutation in DNA mismatch repair genes

~80% progress to CRC

Proximal colon always involved

IBD, tobacco, large villous adenomas, juvenile polyposis syndrome, Peutz Jeghers

Rectosigmoid > Ascending > Descending

Exophytic mass

| Iron deficiency anemia, wt loss

Infiltrating mass

Produces partial obstruction

Colicky pain, hematochezia

Rarely, but can, present as Streptococcus bovis bacteremia

Iron Deficiency Anemia in males >50 and postmenopausal females

Screen for pts >50 with colonoscopy or stool occult blood test

CEA tumor marker is a screen for recurrence

Apple core lesion on barium enema XR

Microsatellite instability pathway (15%)

| APC/beta catenin (chromosomal instability) pathway (85%)

DNA mismatch repair gene mutations --> sporadic CRC and Lynch Syndrome

Mutations accumulate but no defined morphologic correlates

"AK-53" Normal Colon --> loss of APC gene --> decreased intracellular adhesion and increased proliferation --> Colon at risk --> K-RAS mutation --> unregulated intracellular signal transduction --> Adenoma --> Loss of p53 --> Increased tumorigensis --> Carcinoma

NeuroEndocrine tumor 50% of small bowel tumors Appendix, ileum, and rectum EM: Dense core bodies Produces 5HT "CARC" --> Cutaneous flushing, Asthmatic wheezing, R heart murmurs, Cramps (diarrhea) Symptoms only observed if metastases exist beyond liver because liver will degrade 5HT Resection, Octreotide, Somatostatin

Diffuse fibrosis w/ nodular regeneration --> destruction of normal architecture of liver

Macronodules

Regenerative nodules and bridging fibrosis

Increased risk for hepatocellular carcinoma

Alcohol (60-70%), viral hepattis, biliary disease, hemochromatosis

Esophageal varicies --> Hematemesis + melena

Peptic ulcers --> melena

Splenomegaly

Caput Medusae

Ascites

Gastropathy

Hemorrhoids

Coma, Scleral icterus, Fetor Hepaticus, Spider Nevi, Gynecomastia, Jaundice, Testicular atrophy, Asterixis, Bleeding tendency, Anemia, Ankle Edema

AST and ALT are Liver Enzymes

Marker for Liver Pathology

ALT > AST --> Viral Hepatitis

AST > ALT --> Alcoholic Hepatitis

ALP

| Hepatocellular carcinoma, bone disease, bile duct disease

ALP

| Hepatocellular carcinoma, bone disease, bile duct disease

Elevated in liver and biliary disease but not in bone disease

Acute Pancreatitis or Mumps

Acute Pancreatitis

Decreases in Wilson's Disease

Fatal Childhood Hepatoencephalopathy

Rare

Child given aspirin for viral infection (especially VZV and Influenza B)

Mitochondrial abnormalities, Fatty Liver (microvesicular fatty change)

Hypoglycemia, vomiting, hepatomegaly, coma

Aspirin metabolites --> decreased beta oxidation by reversible inhibition of mitochondrial enzymes

Kawasaki's Disease

Steatosis --> Hepatitis --> Cirrhosis

Short term change in liver with moderate alcohol intake

Macrovesicular fatty change of hepatocytes

Reversible with cessation

In order to develop, one needs sustained, long term consumption

Swollen, necrotic hepatocytes with neutrophilic infiltration. Mallory Bodies (intracytoplasmic eosinophilic inclusions)

AST > ALT (usually AST/ALT > 1.5) "make a toAST with alcohol!"

Irreversible

Micronodular, irregular, shrunken liver with "hobnail" appearance

Sclerosis around central vein (zone III)

Manifests as chronic liver disease (jaundice, hypoalbuminemia…)

Most common primary malignancy of the liver in adults

Increased risk w/ Hepatitis B and C, Wilson's, Hemochromatosis, Alpha 1 antitrypsin deficiency, Alcoholic cirrhosis and carcinogens (e.g. aflatoxin from Aspergillus)

Jaundice, Tender Hepatomegaly, Ascities, Polycythemia, Hypoglycemia

Increased Alpha Fetoprotein

Spreads hematogenously

May lead to Budd Chiari Syndrome

Common, benign liver tumor

Age 30-50

Biopsy contraindicated because of risk of hemorrhage

Benign liver tumor

Related to oral contraceptives or steroid use

Can spontaneously regress

Malignat tumor of endothelial origin

| Associated with exposure to arsenic, polyvinyl chloride

Mottled appearance because of backup of blood into liver

R sided heart failure or Budd Chiari

Can result in centriolobular congestion and necrosis which will lead to cardiac cirrhosis

Occlusion of IVC or hepatic vein --> centriolobular congestion and necrosis --> congestive liver disease

Hepatomegaly, ascites, abdominal pain, varices, visible abdominal and back veins. No JVD

Associated with hypercoagulable state, polycythemia vera, pregnancy, hepatocellular carcinoma

Misfolded gene products aggregate in hepatocellular ER --> cirrhosis

PAS + globules in liver

Panacinar emphysema because of decreased elastic tissue in lung

Codominant trait

Yellow skin +/or sclera resulting from elevated bilirubin

| Caused by Direct hepatocellular injury, Obstruction of bile flow, Hemolysis

Direct/Indirect

Increased

Normal or Decreased

Direct

Increased

Decreased

Indirect

Absent (acholuria)

Increased

Immature UDP Glucuronyl transferase --> unconjugated hyperbilirubinemia --> jaundice/kernicterus

Phototherapy (converts UCB to water soluble form)

Gilbert's Syndrome

Crigler-Najjar Syndrome Type 1

Dubin Johnson Syndrome

Mildly decreased UDP-glucuronyl transferase --> decreased bilirubin uptake

Asymptomatic

Elevated unconjugated bilirubin w/o overt hemolysis

Bilirubin increases with fasting and stress

No clinical consequences

Absent UDP-glucuronyl transferase

Presents in early life

Patients die within a few years

Jaundice, kernicterus (bilirubin deposition in brain)

Increased unconjugated bilirubin

Plasmapheresis and phototherapy

Less severe form

| Responds to phenobarbital which increases liver enzyme synthesis

Conjugated hyperbilirubinemia due to defective liver excretion

Grossly black liver

Benign

Mild form of Dubin Johnson Syndrome that does not cause black liver

"Copper is Hella BAD"

Hepatolenticular degeneration

Inadequate hepatic copper excretion and failure of copper to enter circulation as ceruloplasmin

Accumulates in Liver, Brain, Cornea, Kidneys, and Joints

Ceruloplasmin decreased, Cirrhosis, Corneal deposits (Kayser-Fleischer rings), Copper accumulation, Carcinoma (hepatocellular), Hemolytic anemia, Basal ganglia degeneration (parkinsonism), Asterixis, Dementia, Dyskinesia, Dysarthria

Penicillamine, Zn

Autsoomal recessive (chromosome 13)

ATPase (ATP7B gene) transports copper from hepatocytes into bile

Autosomal recessive

Disease caused by iron deposition

Micronodular Cirrhosis, Diabetes Mellitus, Skin pigmentation (bronze diabetes)

Can result in CHF, testicular atrophy, hepatocellular carcinoma

Primary: autosomal recessive mutation of HFE gene (associated with HLA-A3)

Secondary: chronic transfusion therapy (e.g. beta thalassemia major)

Increased ferritin and iron. Decreased TIBC --> Increased transferrin saturation

Repeated phlebotomy, deferasirox, deferoxamine

Extrahepatic biliary obstruction (gallstone, biliary stricture, chronic pancreatitis, carcinoma of the pancreatic head) --> Increased pressure in intrahepatic ducts --> Injury, Fibrosis, and Bile Stasis

Pruritus, jaundice, dark urine, light stool, hepatosplenomegaly

Increased conjugated bilirubin, cholesterol, and ALP

Complicated by ascending cholangitis

Autoimmune reaction --> lymphocytic infiltrate + granulomas

Pruritus, jaundice, dark urine, light stool, hepatosplenomegaly

Increased conjugated bilirubin, cholesterol, and ALP

Also increased serum mitochondrial Abs including IgM

Associated with other autoimmune diseases (CREST, RH, Celiac)

Unknown cause of concentric "onion skinning" bile duct fibrosis --> alternating strictures and dilation with beading of intra and extrahepatic bile ductrs on ERCP

Pruritus, jaundice, dark urine, light stool, hepatosplenomegaly

Increased conjugated bilirubin, cholesterol, and ALP

Hypergammaglobinemia (IgM)

Associated with UC

Can lead to secondary biliary cirrhosis

Increased cholesterol +/or bilirubin, Decreased bile salts, gallbladder stasis

4Fs: Fat, Female, Fertile (pregnant), and Forty

Cholesterol stones and Pigment stones

80% of stones

Radiolucent (10-20% opaque due to calcification)

Associated with Obesity, Crohn's, CF, Age, Clofibrate, Estrogen, Multiparity, Rapid Wt Loss, Native American origin

20%
Radiopaque

Seen in patients with chronic hemolysis, alcoholic cirrhosis, advanced age, biliary infection

Black - hemolysis

Brown - infection

Cholecystitis, Ascending Cholangitis, Acute Pancreatitis, Bile Stasis, Biliary Colic (neurohormonal activation like CCK trigger contraction of gallbladder which forces stone into cystic duct)

Charcot's Triad of Jaundice, Fever, RUQ Pain with a + Murphy's sign (Inspiratory arrest on deep RUQ palpation)

Painless in diabetics

Diagnose with US, Radionuclide Biliary Scan

Cholecystectomy

Fistula between gallbladder and SI --> air in biliary tree

| If gallstone obstructs ileocecal valve, air can be seen on the biliary tree on imaging

Inflammation of gallbladder

Usually from gallstones but can be caused by ischemia or infection (CMV)

Increased ALP if bile duct becomes involved (ascending cholangitis)

Autodigestion of pancreas by pancreatic enzymes

"GET SMASHED"

Gallstones, Ethanol, Trauma, Steroids, Mumps, Autoimmune, Scorpion sting, Hypercalcemia, Hypertriglyceridemia, ERCP, Drugs (Sulfa)

Epigastric pain radiating to the back, anorexia, nausea

Elevated amylase, lipase

DIC, ARDS, Diffuse fat necrosis, Low Ca (collects in pancreatic soap deposits), pseudocysts, hemorrhage, infection, multiorgan failure

Pancreatic pseudocyst (lined by granulation tissue, not epithelium) which can rupture and hemorrhage

Chronic inflammation, atrophy, and calcification of the pancreas

EtOH or idiopathic

Can lead to pancreatic insufficiency, DM, and adenocarcinoma

Amylase and Lipase are increased but less than in acute pancreatitis

Poor prognosis

Arises from ducts in pancreatic head

C-19-9 and CEA (less specific)

Tobacco, Chronic Pancreatitis, Age (>50), Jewish or Black

Abdominal pain radiating to back, Weight loss (malabsorption or anorexia), Trousseau's Syndrome, Obstructive jaundice, Courvoisier's sign

Whipple procedure, Chemo, Radiation

Migrating thrombophlebitis --> redness and tenderness to palpation of extremities