GI Pathology: Large Intestine

What is the main pathology of the appendix

Appendicitis --> inflammatory condition

What is accute appendicitis

acute inflammation of the appendix

What is the most common cause of appendicitis in children

Lymphoid hyperplasia (know this)

What is the most common cause of appendicitis in adults

fecalith = crap rock (know this)

High grade Appendiceal mucinous neoplasms can become what? Where do these spread?

invasive mucinous adenocarcinomas

-invade into the appendiceal wall and spread to the peritoneal cavity

-results in pseudomyxoma peritonei

Most tumors of the peritoneum are

malignant

Primary tumors of the peritoneum are uncommon and mainly include

mesothelioma

This cancer is usually associated with asbestos exposure

Mesothelioma

The following describes what type of tumor histologically

-typically shows papillary growth pattern and contains psammoma bodies

mesothelioma

What is the most common source of metastases of mesothelioma to the peritoneum

ovarian and pancreatic cancers

Pseudomyxoma peritonei arises from

appendiceal mucinous tumors

Where is the principal site of water and electrolyte absorption and formation of fecal masses

Large intestine

What is the most common cause of neonatal intestinal obstruction

Hirschsprung disease

What is Hirschsprung Disease

congenital condition that is due to the absence of ganglia in both submucosa and muscularis externa of the colon and rectum affecting Meissner's and Auerbach's plexuses

What ganglia are missing in Hirschsprung disease

BOTH Meissner's and Auerbach's are missing

The following describes the presentation of what disease

-failure to pass meconium (baby's first poo) during first 48 hours

-leads to abdominal distension and bilious emesis (vomiting bile)

-explosive diarrhea on digital rectal exam is diagnostic

Hirschsprung disease

What 2 things is Hirschsprung disease associated with?

Down syndrome (trisomy 21)

RET gene

KNOW THIS

What is the treatment for Hirschsprung disease

resection of the affected section of the large intestine

What are the inflammatory diseases of the large intestine

infectious colitis

inflammatory bowel disease (Crohn's and UC)

What is a common cause of C. diff colitis

commonly related to prior antibiotic exposure

-especially oral abx

What is the toxin produced by C. diff in C. diff colitis that causes increased mucosal permeability and fluid secretion

toxin a

The following describes the presentation of what disease

-foul-smelling frequent diarrhea

-diarrhea initially watery but may become bloody

-fever

-peripheral blood leukocytosis

-abdominal pain

C. diff colitis

The following describe the endoscopic finding of what disease

-yellow-white pseudomembranes are seen

-most commonly in the left colon

-bleed when scraped

C. diff colitis

The following describes the microscopic appearance of what disease

-layered pseudomembrane composed of fibrin, mucin, and neutrophils

-dilated glands are filled with neutrophils and mucin, with degenerating surface or glandular epi cells

C. diff colitis

How do you diagnose C. diff colitis

cytotoxin A assay

-highly specific and sensitive

What is inflammatory bowel disease

idiopathic, chronic, and relapsing condition with genetic predisposition

Chron's disease and ulcerative colitis are both under the umbrella of inflammatory bowel disease. What skin manifestations do they both present

pyoderma gangrenosum

The following describes what disease

-transmural inflammation of the alimentary canal that may involve any part of the GI tract, from mouth to anus, usually ileum and colon, rarely rectum

Crohn's disease

Where does Crohn's occur in the GI tract?

anywhere from mouth to anus

-usually ileum and colon

Transmural inflammation describes what disease

Crohn's disease

The following symptoms are found in what disease

-RLQ pain

-non-bloody diarrhea

Crohn's disease

The following describe features of what disease

-full-thickness inflammation --> can lead to fistulas

-cobblestoning of the mucosa

-bowel wall thickening leading to strictures (string sign on x-ray)

-skip lesions

Crohn's disease

The following describe what disease histologically

-extensive lymphoid infiltrate

-non-caseating granulomas

Crohn's disease

What are some complications of Crohn's disease

malabsorption (if SI involved)

fistulas

Kidney stones and gallstones are associated with what disease

Crohn's disease

What diagnostic test do you use for Crohn's

ASCA (antisaccaromyces antibodies) test = positive

A positive ACSA test is diagnostic for what disease

Crohn's disease

Where in the GI tract does Ulcerative Colitis occur

restricted to colon and rectum

Ulcerative Colitis affects what layers of the GI tract

mucosa and submucosa

Ulcerative Colitis can result in loss of what feature of the colon

haustra

What is the "lead pipe" appearance on x-ray indicative of

Ulcerative Colitis - due to loss of haustras

The following describe histological features of what disease

-ONLY MUCOSA is typically involved

-Crypt abscesses (plugged up crypts of Lieberkuhn with pus and neutrophils) are common

Ulcerative Colitis

What are some complications of Ulcerative Colitis

increased risk of colonic carcinoma (know this)

toxic megacolon

The following are associated with what disease

-increased risk for primary sclerosing cholangitis (know this)

Ulcerative Colitis

Ulcerative Colitis increases risk for

primary sclerosing cholangitis

A positive p-ANCA test is diagnostic for what

Ulcerative Colitis

What is the diagnostic test for Ulcerative Colitis

p-ANCA test

What are diverticula

blind pouches protruding from the alimentary canal

What is the difference between true and false diverticula

True = full wall thickness outpouching

False = partial wall thickness outpouching

What is Meckel diverticulum

remnant of the vitelline duct that is present in the distal ileum

Is meckel diverticulum a true or false diverticula

a true diverticula

What is the most common congenital GI tract malformation

Meckel Diverticulum

Name the Rule of 2's for Meckel Diverticulum

found in 2% of the population

2 inches long

most commonly found during the first 2 years of life

Meckel's diverticulum presents with what sign

painless, rectal bleeding

Meckel's diverticulum greatly increases the risk of

intussusception

What is a Zenker diverticulum

an outpouching of the pharyngeal mucosa through the inferior pharyngeal constrictor muscle just above the upper esophageal sphincter

Is Zenker diverticulum a true or false diverticula

false diverticula - dose not go through all 4 layers

String sign on CT suggests what and is common in what disease

suggests stricture

common with Crohn's

Zenker's diverticulum is more common in what patient population

elderly males

The following presentation suggests what

-pt presents with dysphagia and halitosis

Zenker Diverticulum