pathology of small bowel and colon Flashcards
what is the Pathogenesis of celiacs disease
Cytotoxic and autoantibody formation → inflammation ( ↑ T-lymphocytes) → villous atrophy → tissue damage → loss of mucosal and brush-border surface area → malabsorption, diarrhea
Celiac’s is Association with other autoimmune diseases:
Type 1 DM, thyroiditis, Sjögren syndrome
what is the CLASSICAL presentation of celiacs disease:
Bulky fatty diarrhea, flatulence, weight loss, anemia, nutritional deficiencies, growth failure in children
what is the Serological diagnosis of celiacs disease
IgA antibodies to tissue transglutaminase
Anti-endomysial antibodies
NORMAL SMALL INTESTINAL MUCOSA should have a Villi to crypt length ratio of ____
~4:1 ratio
Celiac disease often presents with what 4 extra-intestinal complaints:
- Fatigue
- Iron deficiency anemia
- Pubertal delay, short stature
- Aphthous stomatitis (canker sores)
celiacs is Associated with ______, a blistering skin disease
dermatitis herpetiformis
Describe tropical sprue and its prevalence
Post-infectious Tropical Malabsorbtion with No single causative infectious agent.
Prevalent in Haiti, the Dominican Republic,
Puerto Rico, and Cuba and Ind
tropical sprue presents with
Chronic diarrhea
malabsorption (B12,folate, D,E,K,A)
Bacterial overgrowth
epidemiology of peptic disease
Highest incidence in Western countries
Patients >40
Males > Females
PEPTIC DISEASE is Caused by toxic effects on the duodenal mucosa
by _____
excess gastric acid
_________ infection found in majority of patients with peptic ulcer disease
Helicobacter pylori
peptic disease is Most commonly found
in the ________
duodenal bulb
peptic disease Appears nodular or polypoid on endoscopy due to _______ hyperplasia
Brunner gland
microscopic changes seen in PEPTIC DUODENITIS
Villous blunting,
gastric mucin cell metaplasia
Bleeding ulcers cause up to _____ of upper GI bleeding
50%
GROSS FINDINGS-PEPTIC ULCER
DISEASE
Most ulcers found in the duodenal bulb
Ulcers tend to be circular, rarely >3 cm in diameter
Surrounding mucosa appears nodular on endoscopy
due to Brunner gland hyperplasia
a patient has Multiple duodenal ulcers in
association with gastrin hypersecretion by neuroendocrine tumor of pancreas or duodenum, this patient most likely has _________
ZOLLINGER-ELLISON SYNDROME
what is the pathogensesis of WHIPPLE DISEASE
Pathogenesis
Caused by gram-positive bacilli Tropheryma whippelii
Bacilli absorbed by lamina propria macrophages ->
macrophage accumulation within the small intestinal lamina propria and mesenteric lymph nodes → lymphatic obstruction -> Impaired lymphatic transport causes malabsorptive diarrhea
what are the clinical features of WHIPPLE DISEASE
Clinical Features
Triad of diarrhea, weight loss, malabsorption
Other common symptoms: arthritis, lymphadenopathy, neurologic disease
Typically presents in middle-aged or elderly white males
how to diagnose whipple disease
Diagnosis
Tissue biopsy demonstrates the presence of the organisms
what is the incubation period for Giardia lamblia
7-14 days
what is a key microscopic finding in giardiasis
pear-shaped organisms with paired nuclei,
located in lumen
In the US, ______ is a major source of transmission of giardiasis
water
what are the 4 infectious causes of colitis
Bacterial enterocolitis
Pseudomembranous colitis
Viral gastroenteritis
Parasitic enterocolitis
what are 2 Non-infectious causes of colitis
Ischemic colitis
Microscopic colitis
PSEUDOMEMBRANOUS COLITIS is Most often caused by _________ and is common in ____ patients (up to 30%).
Clostridium difficile,
hospitalized
Colitis often occurs after course of antibiotic therapy (“antibiotic-associated colitis”). Most frequently implicated antibiotics are ________
third-generation cephalosporins
patients with PSEUDOMEMBRANOUS COLITIS present with
fever, leukocytosis, abdominal pain, cramps, watery diarrhea
IN PSEUDOMEMBRANOUS COLITIS
WHAT IS A “PSEUDOMEMBRANE”?
A “volcano-like” eruption of neutrophils and mucinous debris attached to the surface epithelium
what is the Most common cause of severe childhood diarrhea and diarrheal mortality worldwide
Rotavirus
how does rotavirus cause diarrhea?
Selectively infects and destroys mature enterocytes → villus surface repopulated by immature secretory cells → loss of absorptive function → net secretion of water and electrolytes →osmotic diarrhea
DEHYDRATION = DEATH
what are the clinical features of ISCHEMIC COLITIS
Older individuals with co-existing cardiac or vascular disease
Young patients: long-distance runners, women on oral contraceptives
Mechanical Obstruction: hernias, volvulus
what is the Pathogenesis of ischemic colitis
Lack of blood flow due to:
Low cardiac output
Occlusive disease of vascular supply to bowel
what are the clinical features of MICROSCOPIC COLITIS
Chronic watery diarrhea
Presents primarily in middle-aged and older women
NSAIDs implicated
diagnosis of MICROSCOPIC COLITIS
Endoscopy: Normal
Tissue biopsy shows characteristic lymphocytic inflammation +/- a thickened subepithelial collagen layer
what is irratable bowel syndome (IBS)
Chronic functional bowel disorder
with Abdominal pain, and altered bowel habits
DIAGNOSTIC CRITERIA FOR IRRITABLE
BOWEL SYNDROME = Recurrent abdominal pain, on average, at least 1 day per week in the last 3 months, associated with 2 or more of the following criteria:
- Related to defecation
- Associated with a change in frequency of stool
- Associated with a change in form (appearance) of
stool
describe IBS MACROSCOPIC & HISTOLOGIC
APPEARANCE
Normal
Inflammatory bowel disease (IBD) is a chronic condition resulting from __________
inappropriate mucosal immune activation
IBD encompasses 2 distinct disorders
Crohn(‘s) disease (CD) Ulcerative colitis (UC)
what Epithelial defects are seen in Crohn’s disease
Defects in intestinal epithelial tight junction barrier function, NOD2 polymorphisms (intracellular receptor for microbes)
what epithelium defects are seen in Ulcerative colitis:
Defects in intestinal epithelial tight junction barrier function, ECM2 polymorphisms (extracellular matrix protein)
what Epithelial defects are seen in Crohn’s disease
Defects in intestinal epithelial tight junction barrier function, NOD2 polymorphisms (intracellular receptor for microbes)
what epithelium defects are seen in Ulcerative colitis:
Defects in intestinal epithelial tight junction barrier function, ECM2 polymorphisms (extracellular matrix protein)
what are the Clinical Features of Crohn’s disease
Relapsing and remitting disease
Intermittent attacks of relatively mild non-bloody diarrhea, fever, abdominal pain
what are the Extraintestinal manifestations of Crohn’s disease
Uveitis (inflammation of the middle layer of the eye),
migratory polyarthritis,
sacroiliitis,
ankylosing spondylitis,
erythema nodosum (flat, firm, hot, red, and painful lumps that usually appear on the shins)
what are disease characteristics of Crohns disease
Skip lesions
Ileal involvement (“regional enteritis”)
Transmural chronic inflammation
Inflammatory strictures
Fissuring ulcers, sinus tracts, fistulae
Risk of adenocarcinoma is similar in CD (colonic disease) and UC (25-year cumulative risk approx 10%) and is related to:
Duration of disease
Extent of disease (pancolitis vs localized involvement)
Family history
Extra-intestinal manifestations (i.e. primary sclerosing cholangitis)
what are the clinical features of ulcerative colitis
Bloody diarrhea or loose stools with lower abdominal pain,
cramps,
Symptoms relieved by defecation
what is the Extraintestinal manifestations of ulcerative colitis
Primary sclerosing cholangitis
Pseudopolyps are more common and numerous in which IBD
Ulcerative Colitis
describe the microscopic appearance of Ulcers in crohns
Deep, knife-like
describe the appearance of Ulcers in crohns
Deep, knife-like
describe the Wall appearance in ulcerative collitis
Thinned
DISTINGUISHING MICROSCOPIC FEATURES of CROHN’S DISEASE are:
Granulomas and Fissuring ulcers
DISTINGUISHING MICROSCOPIC FEATURES of CROHN’S DISEASE
Granulomas and Fissuring ulcers
A diverticulum is an _______
outpouching/herniation of the mucosa and submucosa
Diverticular disease is most common in the ______ colon. Prevalence approaches 60% in Western adult populations over age ________. Asymptomatic or intermittent cramping, lower abdominal discomfort
sigmoid,
60
Diverticulosis =
presence of diverticula
Diverticulitis =
inflammation of the diverticula, usually secondary to obstruction
what complications can arise from DIVERTICULITIS
Obstruction
Perforation
Abscess Formation
Bleeding
classic finding in appendicitis?
McBurney’s sign
what is the pathogenesis of appendicitis
Luminal obstruction by stone-like mass of stool (“fecalith”)→ ischemic injury and stasis of luminal contents → inflammatory response