large intestine Flashcards
(38 cards)
what is inflammatory bowel disease ?
Chronic condition resulting from inappropriate mucosal immune activation
Idiopathic etiology
unknown cause
how to distinct between ulcerative colitis and crohn disease ?
Regional enteritis because of frequent ileal involvement is based on :
1-Distribution of affected site
2- Morphology
Crohn disease : more general affect the entire GIT column
Ulcerative colitis : ulceration in the colon
what are the common features of IBD?
Female > males
whites
Adolescence or in young adults
Developed countries
Colonic inflammation
Similar Rx
Both have increased cancer risk
describe the pathogenesis of IBD ?
idiopathic unknown
Combination of aberrant host interaction with intestinal microbiota , intestinal epithelial dysfunction and aberrant mucosal immune responses
Normal GIT :
Unresponsive to normal intestinal microflora
Responds against ingested pathogen
IBD :
Strong immune response against normal flora
Defects in epithelial barrier function
It is thought to result from UNREGULATED AND EXAGGERATED LOCAL IMMUNE RESPONSE to commensal microbes in the gut , GENETICALLY SUSCEPTIBLE INDIVIDUALS
Failure of immune regulation
Genetic susceptibility
Environmental triggers
describe the immune response in IBD?
T cell mediated response
Particularly CD4+ T cells
Lesions are likely to be caused BY T CELLS and their products
describe the immune response in crohn disease ?
Polarization of helper T cells to TH1 type
Delayed- type hypersensitivity reaction INDUCED by IFN-Y producing T helper 1 cells
Presence of GRANULOMAS is CONSISTENT WITH TH1 RESPONSE
SO :
T helper 1 —> IFNY –> MACROPHAGES —> GRANULOMAS
describe the immune response in ULCERATIVE COLITIS?
Significant TH2 mediated component
NO GRANULOMAS
how do we diagnose IBD?
CD and UC have characteristics clinical and pathologic findings
Based on clinical history, RADIOGRAPHIC EXAMINATION, Laboratory finding, HISTOPATHOLOGY
in some cases differentiation is not possible
Autoantibodies : pANCA -> perinuclear antineutrophilic cytoplasmic antibody ) is positive in :
75% WITH Ulcerative colitis
11% —-> CROHN DISEASE
What is crohn disease ?
Idiopathic chronic regional enteritis that most commonly affects TERMINAL ILEUM
but has the potential to affect any part of GIT
describe the distribution of Crohn disease ?
Might involve the whole GIT :
From the mouth to the anus
small bowel alone –> 40% ( most common in small intestine )
colon alone —> 30%
Both sites —> 30%
describe the gross morphology of crohn disease ?
Sharply delimited and typically TRANSMURAL ( ALL LAYERS ) of the bowel by an inflammatory process with mucosal damage
Segmental with SKIP AREA lead to alternative name REGIONAL ENTERITIS —> so area with and area without INTERMITTENT
Lumen is narrowed
Mucosa FISSURING WITH COBBELESTONE APPEARANCE
Fistula and sinus : Bowl to bowel , Bowel to skin or anus
Thickening of mesentery
describe crohn disease HISTOPATHOLOGY?
Mucosal inflammation , Distortion, Ulceration
Transmural involvement ( ALL LAYERS)
Noncaseating granulomas :
Present in 50% of the cases
When present strongly favor CD
May occur in any part of bowel or adjacent lymph nodes
Absence does not EXCLUDE CD ( if no granuloma that doesnt mean its not CD )
Dysplasia and carcinoma :
Long standing disease
Less frequent compared to ulcerative colitis
describe the clinical presentation of Crohn disease ?
Intermittent attacks of relatively mild diarrhea , fever, abdominal pain
Fibrosing strictures , particularly of the terminal ileum
Fistulas to other loops of bowel or anus
EXTRAINTESTINAL MANIFESTATION —> SINCE ITS IMMUNOLOGICAL DISEASE IT WILL AFFECT OTHER SYSTEMS :
Migratory polyarthritis , Sacroiliitis , ANKYLOSING , SPONDYLITIS
Erythema NODOSUM, CLUBBING OF THE FINGERTIPS
Hepatic primary sclerosing cholangitis
describe the epidemiology of Crohn disease ?
Annual incidence in the united states around 3 per 100k
Peak ages of detection are the second and third decades
Whites appear to develop the disease 2-5 more often compared to non whites
In uas, CD occurs three to five times more often among JEWS than among non jews
Smoking IS A STRONG EXOGENOUS RISK FACTOR
what is ulcerative colitis ? UC
Ulcero inflammatory disease limited to the COLON ONLY
only affect the mucosa and submucosa ( not transmural )
Except in most severe cases
Continuous fashion and not intermittent like Crohn
Proximally from the rectum
NOOOOOOOOOO GRANULOMAS
it is systemic disorder like crohn :
migratory polyarthritis, sacroliitis , ankylosing spondylitis, Uveitis,
HEPATIC INVOLVEMENT –> pericholangitis and pirmary sclerosing cholangitis
PaNCA –> 75% of cases
Crohn was 11% cases
TH2 cells
describe ulcerative colitis Gross morphology ?
Red and granular mucosal lesions
Ulceration –> maybe confluent with regenerating mucosa forming PSEUDOPOLYPS
No mural thickening, serosal surface is usually COMPLETELY NORMAL
TOXIN MEGACOLON –> bowel wall THINS and the mucosa is SEVERE ULCERATED , MAY LEAD TO PERFORATION AND DEATH
Backwash ileitis —> INVOLVEMENT OF DISTAL ILEUM WITH EXTENSIVE DISEASE , OF LITTLE CLINICAL SIGNIFICANCE
describe the histopathology of ulcerative colitis ?
Acute inflammation of crypts :
PMN infiltration of mucosa
Crypt abscess formation ( not specific for UC )
Chronic changes:
Crypt architecture distortion –> crypts may be branched or shortened
Some patients have BASAL PLASMA CELLS AND MULTIPLE BASAL LYMPHOID AGGREGATES
THIS FINDING INDICATES CHRONICITY AND HELP DISTINGUISH UC FROM INFECTION OR SELF LIMITED COLITIS
Dysplasia :
Maybe present in the long standing disease
Surveillance colonoscopy with biopsies recommended
describe UC epidemiology ?
4 to 12 per 100k population
Slightly greater than CD
whites > blacks
females > males
nonsmoking is associated with UC
peak onset between ages 20 and 25
what is the clinical presentation of UC?
Relapsing disorders marked by ATTACKS OF BLOODY MUCOID DIARRHEA WITH TENESUM
must be distinguished from infectious colitis
97% of patient have at least one RELAPSE during a 10 year period
30% of patients require colectomy within the FIRST 3 years of onset due to UNCONTROLLABLE DISEASE
Describe polyps and their type?
most common in the colon
Sessile —> without stalks
Pedunculated : with stalks
Intestinal polys are 2 types :
Neoplastic : most common in adenoma
Non neoplastic : Inflammatory, hamartomatous , hyperplastic
if we have neoplastic then we should be afraid if its :
Very large = higher rate of malig transformation
VIllous appearance = bad
describe non neoplastic polyps?
Hyperplastic polyps or INFLAMMATORY
small less than 5 mm in diameter
Usually positioned on the tops of mucosal folds
Serrated glands with increased GOBLET CELLS and NO DYSPLASIA
describe Hamartomatous polyps ?
Benign tumor composed of OVERGROWTH of mature cells and tissues THAT NORMALLY OCCUR in the affected apart BUT DISORGANIZATION
Describe juvenile polyps?
Most common 80%
less than 5 years of age ( IN CHILDREN )
Located in the rectum
Bleeding per rectum of prolapsed polyp
Pedunculated ( with stalk ) larger than 3 cm
Characteristics CYSTIC SPACES on cut section
Microscopic examination show the spaces to be DILATED GLANDS FILLED WITH MUCIN AND INFLAMMATORY DEBRIS
describe PEUTZ JEGHER SYNDROME?
Rare, autosomal dominant condition
Multiple hamartomatous polyps scattered through out the entire GIT
Melanotic mucosal and cutaneous pigmentation : Lips , oral mucosa, face , genitalia and palmar surface of the hands
While these HAMARTOMATOUS POLYPS dont have malignant potential
patients with the syndrome have an INCREASED RISK OF DEVELOPING CARCINOMAS of PANCREAS BREAST , lung , ovary and uterus
