DERS 08 - GIT Pathology 4 - Small Intestine 2 & Large Intestine Flashcards
1
Q
What is inflammatory bowel disease (IBD)? What are the subtypes of it?
A
A group of chronic relapsing inflammatory disorders of the small and large intestines.
- Ulcerative colitis (UC)
- Crohn’s disease (CD)
2
Q
What is believed to be the etiopathogenesis of IBD?
A
- The patient has abnormal reactivity to GIT bacteria. The reason for this is mostly idiopathic, but genetics and/or past infections are thought to have a role
- In the colon (UC), bacterial components cause enterocytes to release IL-8 and activate dendritic cells to release IL-23 and present the bacterial components to CD4+ T cells. All of this leads to neutrophil activation and inflammation
- In the small intestine (CD), it is believed the bacterial components cause activation of macrophages which release TNF and cause granuloma formation
3
Q
What are the intestinal clinical manifestations of IBD?
A
- The following either occur chronically or in a relapsing fashion and often flare up with physical or mental stress:
- Bloody mucoid diarrhea
- Lower abdominal pain/cramps
- Tenesmus (a continual/recurrent inclination to have a BM)
- With CD, malabsorption or subacute intestinal obstruction can occur
4
Q
What are the extraintestinal clinical manifestations of IBD?
A
- Seen more commonly in UC, the following may develop before the onset of GI symptoms
- Fever
- Weight loss
- Increased risk of developing malignancy
- Migratory polyarthritis
- Sacroileitis
- Ankylosing spondylitis (spinal arthritis)
- Erythema nodosum (inflammation of subcutaneous fat resulting in painful red bumps)
- Clubbing
- Primary sclerosing cholangitis
5
Q
Describe the disease distribution differences between UC and CD.
A
- UC - typically begins in the rectum and spreads through the colon (it can affect the terminal ileum causing backwash ileitis). Usually only affects the mucosa and submucosa but does so diffusively (not patchy).
- CD - typically affects the ileum and colon but can affect the upper GI as well. Usually causes transmural inflammation and granulomas but in a patchy pattern, often referred to as skip lesions
6
Q
Describe the differences in the populations affected by UC and CD
A
- UC - whites usually between 20-25yo
- CD:
- Common in U.S.
- Adolescents and young adults
- F>M
- More common in Jews
7
Q
Describe the gross features of UC
A
- Diffuse loss of mucosal folds starting at the rectum and moving proximally. Replaced with a red, granular, and friable mucosa
- There will often be a sharp demarcation line where the UC stops
- Remaining mucosal folds develop pseudopolyp
8
Q
Describe the gross features CD
A
These all appear in discontinuous regions of the intestines. Known as skip lesions
- Colonic stricture formation due to mural thickening
- Linear mucosal ulcers with cobblestone appearance
- Possible bowel perforation with serositis
- Fat appearance on and in the bowel (creeping fat). Also present in UC
See image
9
Q
Describe the histological appearance of UC
A
- Disease is limited to mucosa and submucosa (lamina propria and muscularis mucosae)
- Cryptitis - neutrophils present in the epithelium of the crypts of lieberkuhn
- Pseudopylroic (gastric) metaplasia of the crypt epithelium
- Misshapen crypts (also seen in Crohn’s)
10
Q
Describe the histological appearance of CD
A
- Dense lymphoid aggregates and granulomas seen transmurally (chronic inflammation)
- Non-caseating epitheliod granulomas
- Misshapen crypts (also seen in UC)
See image
11
Q
What are the clinical features all colitises have in common?
A
- Diarrhea (mucoid or bloody)
- Abdominal pain (usually below umbilicus)
- Abdominal cramps
- Tenesmus (the feeling of needing to have a BM even when bowels are empty)
12
Q
Facts to know about Amebic colitis
A
- Infectious parasitic form of acute colitis caused by Entamoeba histolytica (a protozoan)
- Fecal-oral route
- Can develop into a chronic destructive colitis with flask shaped ulcers
- May involve liver, lung, brain
- Treated with anti-parasitic agents
- May resemble IBD on biopsy because E. histolytica looks like foamy histiocytes, but they ingest RBCs and often have red dots in them. See image
13
Q
Facts to know about Enteric Fever
A
- AKA - Thyphoid fever
- Typic of infectious colitis caused by salmonella typhi
- Presents with fever, headache, abdominal pain, rash, and diarrhea
- Longitudinal ulcers, typically over peyer patches
14
Q
Facts to know about TB infectious colitis
A
- Chronic abdominal pain
- Most commonly found in terminal ileum but usually found in many spots in the jejunum and ileum
- Lesions appear as circular or oval ulcers lying transversely. Typically there are single large ulcers or multiple small ulcers
- Necrotizing (caseating) granulomas
15
Q
How to distinguish between TB colitis and Crohn’s Disease
A
- Large necrotizing granulomas in TB
- Fissuring ulcers not seen in TB
- Transvers ulcers in TB, longitudinal ulcers in Crohn’s
20
Q
Describe the histological appearance of pseudomembranous colitis
A
- The crypts are dilated and extend from muscularis mucosae to the lumen
- Crypts are filled with fibrinous mucopurulent necrotic debris that they’ve released onto the luminal surface to form a pseudomembrane
