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Initial biopsy evaluation should
begin with a careful examination of the requisition to ascertain the
relevant clinical features of the patient and to ascertain the biopsy
site.
Communication between the clinician and the pathologist is essential for
evaluation of all small biopsy specimens.
Reasons for
small bowel biopsy :
1. Evaluation of patients
with malabsorption
2. Investigation of iron deficiency anaemia
3. Monitoring of coeliac disease
4. Diagnosis of neoplasia
5. Investigation of patients with diarrhoea particularly in patients
where infection is suspected. Eg. AIDS
6. In some cases enteroscopy may be performed to confirm NSAID induced
ulceration or when there is bleeding from an unknown site.
Handling of the
specimen:
Proper orientation of the specimen is absolutely essential for the
interpretation of the biopsy.
Four duodenal biopsies are routinely taken .
The specimens are mounted on a filter paper, with the mucosa side up and
placed in a fixative.
After the tissue is processed, it is embedded perpendicular to the
mounting material.
Each specimen is serially or step sectioned in atleast three levels.
The
following clinical data
should
be provided to the pathologist:
Age and sex of the patient ;
Signs and symptoms ; Site of the biopsy ; Endoscopic findings ;
Radiological findings;
Clinical diagnosis;
Previous medical and surgical history ;
H/O intake of drugs or alcohol ;
H/O immunosuppression; Findings of previous biopsies.
Methods of
obtaining biopsy from the small intestine:
1) Suction biopsies 2)
Endoscopic biopsies :
Formerly, suction biopsies were
taken from the jejunum. Crosby suction capsules were used.
Biopsies were larger in size and were more easily orientated in the
laboratory.
Now endoscopic mucosal biopsies have replaced suction biopsies because of
its convenience for the patient and its speed.
Endoscopic biopsy specimens are smaller and since it is performed under
direct vision more specimen can be obtained.
Normal histology of
the small intestine: click here
In the duodenum there is
gradual transition in the epithelial types across the gastroduodenal
junction.
Proximal duodenum may contain islands of typical antral type mucosa and
'transitional epithelium' consisting of cells showing both antral and
intestinal features.
Villi are shorter and broader than jejunum
Submucosal Brunner's glands are present (contains neutral-PAS positive
mucin in contrast to alcian blue positive acid sialomucin of goblet
cells).
Ileum contains more number of goblet cells and villi are shorter and more
fingerlike in shape.
Peyer's patches are more prominent in the ileum.
The report
should include the following information:
- Number and
site of the biopsies
- Are the biopsies normal
or abnormal?
-Villous height
and architecture -
Identification of four normal
villi in a row suggest that the
villous architeture of the
entire specimen is normal.
The villous architecture may be normal, broad or blunted.
Villous height is shortened : Partial villous atrophy (mild, moderate ,
severe) and subtotal villous atrophy.
-Patterns of
abnormal small bowel architecture -
1. Diffuse severe villous
abnormality:
Eg. Celiac disease (gluten sensitive enteropathy),
2. Variable villous
abnormality with specific histological appearance:
Whipples disease; Parasitic infestation; Intestinal lymphangiectasia
; Immunodeficiency syndrome; Enteropathy associated T cell lymphoma;
Abetalipoproteinemia;
Eosinophilic gastroenteritis.
-Villous height
: crypt length ratio -
The ratio of villous height to crypt length in the normal small intestine
varies from about 3:1 to 5:1.
-Presence of
crypt hyperplasia -
Characterized by increase in the length of crypts, a reduction in the
normal villous : crypt ratio and increased number of mitotic figures due
to extension of the proliferative compartment from the crypt bases along
the length of the crypt .
-Surface
enterocytes -
normal, flattened or
damaged
-Brush borders -
preserved or lost
-Intraepithelial
lymphocyte count -
Normal
count is usually less than 30 per 100 surface epithelial cells. IEL count
is more than 40 per 100 epithelial cells in celiac disease.
-Foveolar
metaplasia -
In chronic duodenitis.
-Microorganism -
Giardia
; Cryptosporidium ; Microsporidium
; Mycobacterium avium intracellulare.
-Neoplasia
-
Presence of benign or
malignant tumour. Eg. Adenoma or carcinoma;
Carcinoid ;
Lymphoma
Special stains
commonly performed :
Histochemistry:
1.PAS stain:
Demonstrate macrophages in
Whipple's disease, highlight fungi , foveolar metaplasia in chronic
duodenitis and integrity of the brush border.
2.Wade Fite
or Ziehl Neelson :
Mycobacteria
3.Giemsa or
mucicarmine: Microorganisms
like Cryptosporidium and Microsporidium.
4.Trichrome
stain: Confirm collagen
deposits in ischaemia or collagenous sprue.
5.Iron
hematoxylin counterstain in trichrome technique:Giardia
lamblia
Immunohistochemistry for
neoplastic lesions:
1. CD34-
for stromal tumours
2. S100
protein - neural
differentiation in stromal tumour
3. SMA and
desmin - demonstrate
myogenic differentiation in stromal tumour.
4. Lymphoid
markers- Lymphoma.
5. NSE,
Chromogranin-
Neuroendocrine differentiation of tumour.
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