Small Intestine and Colon Pathology 2 Flashcards
What is the most common cause of acute diarrhea?
Infectious diarrhea
C. difficile associated colitis sx spectrum?
Mild diarrhea to fully developed pseudomembranous colitis to fulminant disease w/perforation or toxic megacolon
C. difficile associated colitis pathology
Colonize human GI tract after normal flora altered by antibiotic therapy
Pseudomembranous colitis
Necrotic crypt cells with mucin, fibrin, and neutrophils and production of a pseudomembrane
Diagnostic test for C. difficile
Stool PCR assay to detect toxin producing C. Difficile strains
Inflammatory bowel disease
- -Composed of chronic ulcerative colitis and Crohn’s disease
- -Inappropriate immune reactions to luminal bacteria that activates mucosal immunity and suppresses immunoregulation
Age range that IBD often presents
15-30 and 50-80 yrs
Long-term complication of IBD
Intestinal adenocarcinoma (colitis associated dysplasia)
Ulcerative colitis
- -MUCOSAL DISEASE
- -Limited to colon and rectum in continuous fashion
- -“Left-sided disease of colon”
Ulcerative colitis where only the rectum is involved
Ulcerative proctitis
What is basal plasmacytosis associated with?
Chronic cholitis
Pathology of ulcerative colitis
- -Shallow ulcers with residual pseudopolyp mucosa
- -Lymphoplasmacytic inflammation
What is architectural distortion associated with?
Chronic inflammatory process
What does it mean when neutrophils perforate the crypt epithelium (neutrophilic cryptitis)?
Acute inflammation occurring and colitis considered active
Clinical manifestations of ulcerative colitis
- -Bloody diarrhea w/mucus discharge
- -Lower abdominal pain and cramps
- -Tenesmus (secondary to proctitis)
Diagnostic test for ulcerative colitis
pANCA +
Complications of ulcerative colitis
Fulminant colitis w/toxic megacolon–> can cause perforation
Crohn’s disease
- -Transmural inflammatory changes (more layers than mucosa)
- -Can involve any layer of the inflammatory tract
- -Skip lesions (not continuous)
Pathology of Crohn’s disease
- -Typically involves ileum
- -Inflammatory polyps
- -Can present as aphthous ulcers
- -Extends into submucosa and underlying muscle wall
- -Cobblestone appearance of mucosa
- -“Creeping fat”
- -Fistula tract may be present
- -Non-caseating granulomas may be present
Clinical manifestations of Crohn’s disease
- -Variable
- -Usually starts with bouts of mild diarrhea, fever, abdominal pain
What can sometimes trigger Crohn’s disease
Cigarettes
What do 10-20% of patients with Crohn’s disease have?
–Extra-intestinal disease (primary sclerosing cholangitis, erythema nodosum, pyoderma gangrenosum, iritis/uveitis, HLA B27+ sacroiliitis/arthritis)
Diagnostic test for Crohn’s disease
ASCA +
Complications of Crohn’s disease
Small bowel strictures, bowel obstruction, bowel perforation w/fistula formation
Indeterminate colitis
Pathological overlap between UC and CD. Serologic studies may help
Quiescent colitis
- -Following therapy
- -Persistent crypt architectural distortion w/o inflammation
Diversion colitis
- -Colitis developing in blind distal segment of colon (excluded from fecal stream)
- -Following surgery w/formation of diverting ostomy
Diversion colitis cause
–Deficiency in short-chain fatty acids
Pathology of diversion colitis
- -Mucosal erythema
- -Friability
- -Nodularity
Tx of diversion colitis
Re-anastomosis w/return to normal fecal stream or SCFA enemas
Radiation entercolitis
- -Occurs when GI tract irradiated
- -Epithelial damage acutely
- -Chronic injury ischemic from vascular injury
Pathology of radiation enterocolitis
- -Ulcers, strictures, fistulas, serosal adhesions
- -Patchy erythema, secondary to mucosal telangiectasias w/blood vessel hyalinization and thickened walls.
- -Radiation fibroblasts may be present
Neonatal necrotizing enterocolitis
- -Can develop during 1st week in premature infants
- -Small and large bowel necrosis (can become transmural)
- -Bacterial overgrowth produces gas in intestinal wall
Pneumatosis intestinalis
- -Bacterial overgrowth causing gas in intestinal wall
- -Can be seen in neonatal necrotizing enterocolitis
Microscopic colitis
- -Chronic watery diarrhea
- -Normal colonoscopy w/intact crypt architecture
- -Though to be autoimmune mechanism
- -Associated with Celiac disease
- -Tx: glucocorticoids
2 types of microscopic colitis
Lymphocytic colitis
Collagenous colitis
Lymphocytic colitis
- -Increased lamina propria chronic inflammation
- -Increased plasma cells
- -Increased intraepithelial lymphocytes
- -Increased surface epithelial damage
Collagenous colitis
- -Band of subepithelial collagen in addition to changes seen in lymphocytic colitis
- -Increased lamina propria chronic inflammation
- -Increased plasma cells
- -Increased intraepithelial lymphocytes
- -Increased surface epithelial damage
Classes of drugs implicated in drug induced enterocolitis
NSAIDs
Chemotherapeutic lesions
Antibiotics
Irritable bowel syndrome
- -Chronic, relapsing abdominal pain or discomfort, bloating and change in bowel habits (diarrhea or constipation)
- -Absence of any known causative agent that could explain the sx (diagnosis of exclusion)
Endoscopic and colonoscopic findings of IBS
No abnormalities
Prevalence of IBS
5-10%
Pathogenesis of IBS
- -Not known
- -May be related to increased/decreased colonic contraction/transit rates, excess bile acid synthesis, malabsorption of bile acids, disturbance in enteric nervous system function, immune activation, shift in gut microbiome
Ischemic bowel disease causes
- -Arterial obstruction/thrombosis
- -Mesenteric venous thrombosis
- -Hypoperfusion
Bowel segments affected in ischemic bowel disease
–Segments located near end of arterial supply (splenic flexure, sigmoid colon, rectum)
Complications of transmural bowel necrosis
- -Sepsis
- -Septic shock
- -Death
Presentation of acute mesenteric ischemia w/transmural necrosis
- -Sudden onset abdominal pain
- -Loss of bowel sounds
- N and V
- -Bloody diarrhea (melanotic, dark, tarry stool)
Diagnosis of acute mesenteric ischemia w/transmural necrosis
High level of suspicion and demonstration of vascular obstruction
Presentation of chronic mesenteric ischemia
- -Abdominal pain following eating (mesenteric angina)
- -Bouts of bloody diarrhea may occur
- -Sx can mimic inflammatory bowel disease
Angiodysplasia
Lesion consisting of malformed submucosal and mucosal blood vessels. Dilated tortuous capillaries in mucosa
Clinical presentation of Angiodysplasia
Occurs in cecum and R colon in older adults. Bleeding can be acute and massive or chronic and intermittent
Ischemic bowel disease population?
Generally older individuals w/coexisting CV disease
Pathology of ischemic bowel disease
- -Mucosal ischemic injury–> atrophy/loss of surface epithelium, hemorrhagic and hyalinized lamina propria, crypt atrophy
- -Severe injury leads to coagulative necrosis of bowel layers
Prevalence and etiology of angiodysplasia
- -Prevalence: 1%
- -Etiology: uncertain, may be acquired and incidence increases with age
Complication of angiodysplasia
Hematochezia
Diagnosis of angiodysplasia
Colonoscopy and angiography
Sigmoid diverticulitis
Formation of multiple diverticulae in sigmoid colon that are inflamed
Pathology of sigmoid diverticulitis
- -Elevated intraluminal pressure in sigmoid colon
- -Focal discontinuities of inner muscular coat
- -Can can outpouchings of mucosa and formation of diverticulae
Common complications of sigmoid diverticulitis
- -Abscess
- -Obstruction
- -Perforation
- -Fistula
Treatment of sigmoid diverticulitis
–Clear liquid diet and antibiotic followed by high fiber diet. If complicated, may need surgery
Solitary rectal ulcer syndrome
–Malfunction of puborectalis muscle–> excessive straining on defecation–> can lead to mucosal prolapse that can ulcerate and form polypoid abscesses
Who do you usually see solitary rectal ulcer syndrome in?
Relatively young, healthy adults w/blood in stools, pain with defecation, alternating constipation/diarrhea
What can solitary rectal ulcer syndrome mimic?
Adenocarcinoma or ulcers seen in Crohn’s disease
Morphology of solitary rectal ulcer syndrome?
Fibromuscular hyperplasia of lamina propria, inflammation and ulceration, reactive crypt hyperplasia
