Surgical Pathology:- Part 2 – Types of Biopsies
Types of biopsies
How to send the biopsy
- Always send the biopsies in the formalin.
- The commercially available formalin is diluted to 10 % with distal water.
Fixation of surgical pathology
- Formalin aims to fix the tissue to stop the autolytic changes in the biopsies.
- All specimens should be placed immediately following excision into 10% neutral buffered formalin to allow them to “fix”.
- Ideally, the amount of fixative should be at least ten times the volume of the specimen.
- However, this might not be practical in the case of very large specimens (which should be transported to the laboratory as soon as possible).
- Squeezing of small biopsies must be avoided as this can cause cells to become distorted and rendered unidentifiable when examined microscopically.
- Large specimens must not be ‘squeezed’ into too small containers as this compromises fixation and may adversely affect the final report.
- For proper fixation time needed is between 10 to 24 hours.
Precautions for sending the biopsy
- Never send the biopsy in distal water or saline. The tissue will be autolyzed in these liquids, and proper histopathologic changes will not be seen.
Reporting of surgical pathology
- 80% of Diagnostic Biopsies were reported within 7 Calendar Days.
- In urgent cases, a biopsy can be reported in 3 days.
Special biopsies types
Biopsy Specimens for Bacteriological Examination:
- If the biopsy requires bacteriological investigation (for example, a lymph node that may be infected with tuberculosis), then part of the biopsy should also be sent separately without fixative in an appropriate sterile container to the laboratory with a Microbiology request form.
- The Cellular and Anatomical Pathology and Microbiology request forms should be clearly identified with the ‘Danger of Infection’ labels and double-bagged if a high-risk pathogen is suspected (see below).
- Whenever there is suspicion about the possibility of tuberculosis must always be sent in formalin.
The biopsy is done from various tissues like:
- Bone marrow for hematological diseases.
- Breast tissue for benign and malignant diseases.
- Endometrial tissue.
- Esophageal tissue for gastroesophageal reflux disease.
- Small intestine for gluten-sensitive enteropathy.
- Kidney for glomerular disease and lupus nephritis.
- Liver for cirrhosis, hemochromatosis, and fever of undetermined origin.
- Lung biopsy.
- Pleural biopsy.
Liver biopsies for dry copper and iron weight:
- Specimens for dry copper or dry iron weight must be sent dry. Please do not place the specimen in formalin, which will invalidate the result.
Skin biopsy for Hansen’s disease:
- Select the most active margin of the most active lesion.
- Obtain a full-thickness biopsy, including the subcutaneous fat.
- Either elliptical or punch biopsy is OK (a 4 mm punch is sufficient).
- Send in 10% neutral buffered formalin.
- The muscle biopsy sample is immediately divided.
- One portion remains unfixed.
- While smaller portions are placed into formalin and glutaraldehyde fixatives.
- Fix the tissue on the card so that the muscles should remain straight.
- The specimens are then sent to the laboratory for specialized processing and interpretation.
- Routine evaluation of the muscle biopsy sample involves the examination of formalin-fixed, paraffin-processed sections.
- Unfixed frozen sections with standard histological and enzyme histochemical stains at the light microscopic level.
- Immunohistochemical stains are utilized for the diagnosis of various muscular dystrophies.
- Electron microscopic examination of the glutaraldehyde-fixed portion of the biopsy is performed when the light microscopic studies are inconclusive.
- These are done with the help of a needle.
- The material is sent in formalin.
- Special stains and immunochemistry are done to diagnose various types of renal diseases.
Bone marrow biopsy:
- Aspiration of bone marrow is done with a wide-bore needle.
- Trephine biopsy is the real bone tissue that is taken.
Testicular biopsy: This may be:
- An open biopsy is to take surgical tissue from the testes.
- A punch biopsy may be taken when there is small tissue needed.
- FNA is done with a fine needle of 23 or 25 gauge.
Spleen biopsy: This can be taken:
- FNA can be done.
- Also can take a biopsy with a wide bore needle, but there are chances for the possibility of hemorrhage.
Lymph node biopsy: This can be done by:
- FNA can be done.
- Open lymph node biopsy gives better appreciation.
Cervical biopsy: Cervical tissue is taken by curettage or scraping and making the smear.
Questions and answers:
Question 1: What is the purpose of a testicular biopsy?
Testicular biopsy is advised in infertile males.
Question 2: What is the purpose of a kidney biopsy?
Kidney biopsy is done to find the type of glomerulonephritis.
- Note see more details in surgical pathology part 1.