Small Bowel Flashcards
What are some important small bowel parasites?
Protozoa:
- Giardia
- Cryptosporidia
Fungi
- Microsporidia
Bacteria:
- Tropherma whipplei (Whipples disease)
- E. Coli
Flatworm:
- Schistosoma
Describe Giardia
- Trophozoites (protozoan)
- Pear-shaped
- Binucleate (“Monkey face”)
- Faintly basophilic
- Seen between villi, classically in duodenum
- Does not invade
- Sometimes mild villous blunting and IELs
- Looks like falling leaves in the bowel lumen
- Aquired from contaminated water, faeco-oral route, sexually transmitted
- More commen in children, travel and immunocompromised
- Diarrhoea/Malabsorption - watery and foul-smelling
INVESTIGATIONS:
* Stool - cysts
* PCR
STAINS:
* Masson’s Trichrome
* Giemsa
* CD117+
TREATMENT:
* Metronidozole
Des
Describe Cryptosporidia
- Protozoan
- Most common - C. Hominis, C. Parvum
- Acute, watery diarrhoea
- Can last up to four weeks, relapsing and remitting
- Located at apex of epithelial cells along luminal border - dot-like organisms
- Small bowel most common site
- Also colon, stomach, biliary tree, respiratory tract
- Seen in children and immunocompromised patients
- Usually correlates with CD4 counts < 100
- Faeco-oral route
- Basophilic
- Villous blunting
- Mixed inflammatory infiltrate
STAINS:
* Modified Acid-Fast (AFB)
* Giemsa
TREATMENT:
* Nitazoxanide
Describe Microsporidia
- Obligate intracellular organism
- Enterocytozoon bieneusi - best seen in electron microscopy
- Usually seen in the setting of AIDS
- Jejunum shows highest parasitic burden
- Bifringent spores seen as intra epithelial inclusions
- Lamina propria macrophages
INVESTIGATIONS:
* Stool examination
* PCR
* Electromicroscope
STAINS:
* Giemsa
* ZN can highlight spores
Treatment:
* Albendazole
Describe Whipple Disease
- Bacterial infection
- Tropherma whipplei
- Small bowel –> Oesophagus –> Stomach –> Appendix –> Colon
- Malabsorption, diarrhoes, arthralgias, pain, neurological symptoms, lymphadenopathy
- Lamina propria expanded by foamy macrophages
STAINS:
* PAS +ve
* AFB -ve
Associated with HLA-B27
Describe Schistosomiasis
- Mansoni, japonicum, mekongi, hematobium. intercalatum
- Contaminated water in endemic areas
- Focal ulcers
- Eggs may be calcified, surrounded by fibrosis/granuloma
INVESTIGATIONS:
* Eggs in faeces or urine
* Wet mount/Formalin ethyl acetate
TREATMENT
* Praziquantel
Describe E. Coli
- Enterohaemorrhagic E. coli - 0157:H7
- Shiga toxin interferes with protein synthesis –> causes cell damage
- Contaminated food
- Most self-limiting
- Can cause** haemolytic-uremic syndrome **and thrombocytopenic purpura
Micro:
* Mucosal haemorrhage, infarct, pseudomembranes
* Neutropholic infiltrates, cryptitis, crypt abscesses
Diagnosis:
* Serotyping
* PCR
* DNA hybridisation
* E coli O157:H7 –> detected from stool culture with selective growth media
Describe Coeliac Sprue
- Immune mediated
- Caused by sensitivity to prolamins - Wheat (gliadin), Barley (hordein), Rye (secalin), Oats (avenin)
- Duodenum > Ileum
Associated with:
- **Autoimmune diseases **- Dermatitis herpetiformis, T1SM, Hashimotos, Graves)
- Idiopathic diseases - Dilated cardiomyopathy, epilepsy, MS
- Chromosomal diseases - Downs, Turner, William
Can lead to:
- Iron deficiency anaemia (microcytic)
- B12 deficiency (macrocytic anaemia)
- Osteopenia/Osteoporosisa - altered absorption of calcium and vitamin D3
- Growth retardation, tooth enamel defects, stomatitis, hypertransaminasemia
Aetiology:
- HLA DQ2 (98%)
- HLA DQ8
- Ingestion of gluten
Microscopy:
- Shortening of villi (villous atrophy)
- Intraepithelial lymphocytes (>30 per 100 enterocytes or >12 in villous tips)
- Loss of brush border at surface of epithelium
- Increased mitotic activity in crypts
- Crypt elongation and hyperplasia
- May see thickened subepithelial collagen band (collagenous sprue is refractive to treatment with no antibodies)
Classification:
- Marsh Classification
- Based on: IEL, Crypts (normal or increased), Villi (atrophy)
- 0 (normal) to 3c (Destructive)
IHC:
* 70% intraepithelial lymphocytes express CD8
DIAGNOSIS:
Histology of duodenal biopsy and serology
- tTGA (tissue transglutaminase) - highest sensitivity
- EMA (endomysial antibody) - almost absolute specificity
- AGA (IgA class antigliadin) 0 now obsolete
PROGNOSIS:
- Excellent prognosis with gluent free diet
- Enteropathy associated T cell lymphoma in small bowel - seen in pateints with long lasting, well controlled coeliac
- Increased risk of small bowel adenocarcinoma
Describe Tropical Sprue
- AKA Post infective sprue
- May be caused by E. coli or haemophilus
- Tropics (not jamaica), africa, india
- Causes malabsorption within weeks of acute diarrheal enteric infection
- **Ileum **> Duodenum
- No increased risk to intestinal lymphoma
Treatment:
- Broad spectrum antibiotics (tetracycline)
- Folic acid
- Vitamin B12
Describe CVID
- Common Variable Immunodeficiency syndrome
- Primary immune defect
- Reduction in B cells, causing hypogammaglobulinemia (IgG)
- IgA or IgM deficiency
- Frequent infections, recurrent giardiasis
Manifestations:
- Recurrent respiratory infections
- Chronic lung disease (bronchiectasis)
- Autoimmune disease’
- GI disorders
Micro:
- Absence of plasma cells in the lamiba propria (but can be present in some cases)
- Lymphoid aggregates
- Mild villous blunting
- Increased IELs
- May see Giardia
Treatment:
- Immunoglobulin replacement therapy
Describe Abetalipoproteinaemia
- Rare autosomal recessive disorder
- Interferes with normal absorption of fat and fat-soluble vitamins
Symptoms:
- Diarrhea
- Steatorrhea
- Ataxia (Posterior column of spinal cord involved)
- Retinitis pigmentosa
Aetiology:
- MTP deficiency - mutation in microsomal triglyceride transfer protein
Micro:
- Marked fat vacuoles in apical villous cytoplasm
- Normal villi
Lab Features:
- Acanthocytosis on periperal blood smears (burr cells)
- Decreased serum cholesterol
- Low levels of LDL and VLDL
- Low Triglycerides
- Increased high-density lipoprotein cholesterol levels
Treatment:
- High doses Vitamin E
Describe Microvillous Inclusion Disease
- AKA Davidson’s disease or Congenital microvillus atrophy
- Autosomal recessive
- Disorder of intestinal brush border
- Intractable watery diarrhoea with steatorrhoea in infants
- Require TPN
- Rarely live beyond 2 years of age
AETIOLOGY:
* Mutations in the MYO5B gene
* Small amount have STX3 gene mutations
MICRO:
* severe villous abnormality and crypt hypoplasia
* Resembling coeliac sprue without lymphocytosis
* Increased enterocyte apoptosis and proliferation
* Bubbly vaculated apical cytoplasm
* Extensive or patchy absence of brush border
* Definitive diagnosis on electron microscopy - shows microvillus inclusions
IHC:
* PAS
* CD10
CD10 and PAS stain positive within the enterocytes (cytoplasmic staining).
Normal should just be linear brush border staining,
- CEA
Describe Diaphragm disease
- Small bowel pathology related to NSAID use
Macro:
- Small bowel with multiple tight short diaphragm like strictures caused by prominent raised fold of bowel.
- Ulceration at crests of the folds.
Micro:
- Thin circumferential membranes
- Resemble plica circularis
- Composed of mucosa and submucosa with accompanying fibrosis
Treatment:
- Cessation of NSAIDs
Describe Small bowel Adenomas
INTESTINAL TYPE
* Similar to tubular adenoma of colon
FOVEOLAR
* Tubulovillous architecture
* Characteristic mucinous cap
* Prone to high grade dysplasia
PYLORIC GLAND
* Tightly packed tubules
* Monolayer of cuboidal cells with granular eosinophilia cytoplasm
* NO spivsl mucinous cap
Duodenum is most prone to developing adenomas
Molecular:
- Non-ampullary duodenal adenomas (60%) —> associated with FAP or MUTYH-associated polyposis
Describe Gangliocytic Paraganglioma
- Rare tumour of periampullary region
- Second part of the duodenum
- Unencapsulated
- Submucosal
Three characteristic cell types:
* Epithelioid
* Spindle-shaped
* Ganglion-like
- Ususally benign
- 7% can metastasise
IHC:
Epithelial cells
* CD56
* Synaptophysin
* Chromogranin-A
* Somatostatin
* Progesterone receptor
* Pancreatic polpeptide
Ganglion cells
* CD56
* Synaptophysin
* Chromogranin-A
* Somatostatin
* Pancreatic polpeptide
* S100
Spindle cells
* S100
* BCL2
