Gastrointestinal Flashcards
The most common cause of acute abdomen
appendicitis
Appendicitis- causes
1) lymphoid hyperplasia (children)
2) fecaliths (adult)
Appendicitis- presentation
periumbilical pain migrating to RLQ pain, nausea, guarding, rebound tenderness, periappendiceal abscess (complication)
Ulcerative colitis- distribution of inflammation
Ulceration in the mucosa and submucosa, usually extending contiguously from the rectum. May go up to cecum.
Ulcerative colitis- presentation
Bloody diarrhea, LLQ pain
Ulcerative colitis- histology
Crypt abscesses with neutrophils
Ulcerative colitis- gross and radiological findings
Pseudopolyps, loss of haustra (“lead pipe” appearance on imaging)
Ulcerative colitis- complications
Toxic megacolon, carcinoma
Ulcerative colitis- associated disorders
primary sclerosing choleangitis, p-ANCA positivity
Crohn’s disease- distribution of inflammation
full thickness from mouth to anus, often with skip/patchy distribution. Often involves ileum; rarely involves rectum.
Crohn’s disease- presentation
non-bloody diarrhea, RLQ pain
Crohn’s disease- histology
lymphoid aggregates, non-caseating granulomas
Crohn’s disease- gross and radiological findings
cobblestone mucosa, creeping fat, strictures (string-sign with barium)
Crohn’s disease- complications
malabsorption, vitamin D and B12 deficiency, calcium oxalate nephrolithiasis, fistulas, cancer
Crohn’s disease- associated disorders
ankylosing spondylitis, sacroiliitis, migratory polyarthritis, erythema nodosum, uveitis
Duodenal atresia- etiology
failure of canalization in the duodenum
Duodenal atresia- association
Down Syndrome
Duodenal atresia- presentation
polyhydramnios, bilious emesis, “double-bubble” sign
Meckel diverticulum- etiology
failure of vitelline duct to invaginate
Meckel diverticulum- presentation
Symptoms: Often asymptomatic, or bleeding, volvulus, intussusception, or obstruction during first 2 years of life.
Clinical: stool-like feeling in area of umbilicus. 2 inches long in the small bowel within 2 feet of the ileocecal valve.
Volvulus- etiology
Twisting of bowel along its mesentery, leading to obstruction and infarction
Volvulus- location
Sigmoid in elderly; cecum in young adults
Intussusception sign
Currant jelly stool (due to infarction)
Intussusception causes
Lymphoid hyperplasia in children (e.g. virus); tumor in adults
Transmural small bowel infarction- causes
Embolism/thrombosis of superior mesenteric artery or thrombosis of superior mesenteric vein
Mucosal small bowel infarction- causes
Marked hypotension
Small bowel infarction- presentation
Abdominal pain, bloody diarrhea, decreased bowel sounds
Causes of lactose intolerance
Congenital (rare), aging, post-infectious (transient)
Test to rule out celiac
(Negative for) HLA-DQ2 and HLA-DQ8
Celiac- laboratory testing
IgA to tTG, gliadin, endomysium. If IgA is low (common in celiac), check IgG.
Celiac- histology findings
Flattening of villi, hyperplasia of crypts, and intraepithelial lymphocytes. Mostly in the duodenum.
Celiac- complications
Small bowel carcinoma, enteropathy-associated T cell lymphoma (EATL)
Tropical sprue- key differences with celiac sprue
Caused by an unknown organism, follows infectious diarrhea, primarily affects jejunum and ileum (rather than duodenum), and responds to antibiotics
Whipple disease-etiology
Systemic tissue damage. Tropheryma whipplei bacteria are incorporated into macrophages in the lamina propria. These macrophages compress the lacteals and cause fat malabsorption.
Whipple disease- locations outside of GI system
synovium, cardiac valves, lymph nodes, CNS
Abetalipoproteinemia- inheritance and etiology
autosomal recessive deficiency of apolipoproteins B-48 and B-100. B-48 is needed to make chylomicrons, leading to fat malabsorption. B-100 is needed to make VLDL and LDL, so these are absent.
Carcinoid tumor- cell type
neuroendocrine cells
Carcinoid tumor- stain
chromogranin, synaptophysin, cytokeratin
Carcinoid tumor- most common GI location
small bowel
Why isn’t there carcinoid syndrome if it is confined to the small intestine?
5-HT is metabolized to by 5-HIAA by MAO in the liver after going through portal circulation.
Carcinoid syndrome- symptoms
Bronchospasm, diarrhea, flushing
Carcinoid syndrome- aggravating factors
Emotional stress and alcohol
Carcinoid syndrome- cardiac effects and tumor location if these are present
Fibrosis, deposition of collagen within valves of right heart. Tricuspid regurgitation, pulmonary stenosis. Left side unaffected due to MAO in lungs. Tumor located in liver (hepatic vein drains to IVC).
Rovsing’s sign and significance
Pushing on left side of abdomen hurts right side of abdomen; appendicitis (severe)
McBurney’s point and significance
2/3 laterally on imaginary line from umbilicus to ASIS; appendicitis
Murphy’s sign significance
Gallbladder (or liver) inflammation
Hinchey stages and their use
Diverticulitis.
1) small abscess
2) large abscess
3) gaseous release outside colon wall
4) fecal discharge outside colon wall
Diverticulitis- antibiotic combinations
1) metronidazole + quinolone
2) metronidazole + 3rd generation cephalosporin
3) Beta-lactam + beta-lactamase inhibitor (Augmentin)
Paralytic ileus causes
iatrogenic/surgery, narcotics, calcium channel blockers, hypokalemia
Inflammatory pseudopolyps- histology
granulation tissue, inflammatory infiltrate
Hamartomatous polyps- histology
“arborizing” smooth muscle divides glands and crypts
Juvenile/retention polyps- histology
cystic glands, stromal edema, inflammation, surface ulceration
Juvenile polyposis syndrome- genes and inheritance
Autosomal dominant; usually SMAD4 or BMPR1A, sometimes PTEN
Juvenile polyposis syndrome- associations
pulmonary arteriovenous malformation
Cronkite-Canada syndrome- presentation
Like juvenile polyposis in older individual. Abnormal intervening mucosa (unlike JP), diarrhea, weight loss, and symptoms with hair, skin, and nails.
Peutz-Jeghers syndrome- presentation
Hamartomatous polyps throughout GI tract, mucocutaneous hyperpigmentation on buccal mucosa and genitals
Peutz-Jeghers syndrome- genes and inheritance
Autosomal dominant; LKB1/STK11
Cowden syndrome- genes and inheritance
Autosomal dominant; PTEN (chromosome 10)
Cowden syndrome- associations
Macrocephaly, Lhermitte-Duclos disease, benign skin tumors, thyroid tumors, breast tumors, endometrial tumors, Bannayan-Ravulcaba-Riley syndrome
Bannayan-Ravulcaba-Riley syndrome
Cowden syndrome + developmental delay
Familial adenomatous polyposis- genes and inheritance
APC (autosomal dominant) or MUTYH (autosomal recessive)
Familal adenomatous polyposis- associations
Gardner syndrome, Turcot syndrome, congenital retinal pigment epithelial hypertrophy
Gardner syndrome
FAP + fibromatosis + osteomas
Turcot syndrome
FAP + CNS tumors (medulloblastoma and glial tumors)
Hereditary non-polyposis colon cancer (Lynch) syndrome- genes and inheritance. What do the respective proteins do?
Autosomal dominant; usually MSH2 or MLH1 (DNA mismatch repair genes)
Adenoma-adenocarcinoma sequence (GI)- steps
1) APC mutation increases the risk of polyps.
2) KRAS mutation allows formations allow of polyps
3) p53 mutation and increased COX expression cause cancer
APC chromosome location
Chromosome 5
Hereditary non-polyposis colon cancer (Lynch) syndrome- presentation
Fewer polyps that familial adenomatous polyposis, colorectal cancer on the RIGHT side at a young age, sometimes Turcot syndrome
Adenoma-adenocarcinoma sequence (GI)- side
Usually causes left side tumors
Colonic carcinoma is associated with an increased risk of what infection?
Streptococcus bovis endocarditis
Left side colorectal cancer- symptoms
“Napkin ring” lesion causes reduced stool caliber, LLQ pain, blood streaking on stool
Right side colorectal cancer- symptoms
Iron deficiency anemia (slow bleeding), vague pain
What is CEA good for in colorectal cancer?
Monitoring treatment response and recurrence.
What is CEA NOT good for in colorectal cancer?
Screening for colorectal cancer
Right side colorectal cancer- cause
Microsatellite instability sequence
Left side colorectal cancer- cause
Adenoma-adenocarcinoma sequence
Simplified colorectal cancer staging
Stage 1: small tumor
Stage 2: big tumor
Stage 3: regional lymph node involvement
Stage 4: metastasis
Carcinoid tumor- appearance
non-pedunculated bumps with yellow cut surface
Mucus-associated lymphoid tissue (MALT) lymphoma- risk factors
H. pylori infection, chronic inflammation
Mucus-associated lymphoid tissue (MALT) lymphoma- complications
De novo change to diffuse B cell lymphoma
Mucus-associated lymphoid tissue (MALT) lymphoma- cell markers
CD20+, CD5-, CD10-
Gastrointestinal stromal tumor (GIST)- origin
Interstiitial cells of Cajal
Gastrointestinal stromal tumor (GIST)- targeted treatment
Imatinib if c-kit+ (CD117) or PGDFRA+
Pancreatic cancer- metastastis mechanism
Epithelial-to-mesenchymal transition (EMT)
When is ectopic gastric or pancreatic tissue observed?
Meckel (ilieal) diverticulum
Mechanism of osteoporosis in celiac sprue
1) Decreased small bowel absorption of calcium and vitamin D cause osteomalacia
2) Cross-reacting antibodies to osteoprotegerin result in increased osteoclast activation via RANKL
Plummer vinson syndrome triad
Iron-deficiency anemia, atrophic glossitis, esophageal web
Plummer vinson syndrome association
increased risk of squamous cell carcinoma of the esophagus
