Surgical Pathology – Part 2 – Histopathology , Types of Biopsies

How to send the biopsy

1. Always send the biopsies in the formalin.
2. The commercially available formalin is diluted to 10 % with distal water.

Fixation

1. The purpose of formalin is to fix the tissue to stop the autolytic changes in the biopsies.
2. 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.
3. However, this might not be practical in the case of very large specimens (which should be transported to the laboratory as soon as possible).
4. Squeezing of small biopsies must be avoided as this can cause cells to become distorted and rendered unidentifiable when examined microscopically.
5. Large specimens must not be ‘squeezed’ into containers that are too small as this compromises fixation and may adversely affect the final report.
6. For proper fixation time needed is between 10 to 24 hours.

Precautions

• Never send the biopsy in distal water or saline. In these liquids, the tissue will be autolyzed and proper histopathologic changes will be not seen.

Reporting

• 80% of Diagnostic Biopsies reported within 7 Calendar Days.
• In urgent cases, a biopsy can be reported in 3 days.

Special biopsies

Biopsy Specimens for Bacteriological Examination: 

1. 1. 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.
   2. 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).
   3. Whenever there is suspicion about the possibility of tuberculosis must always be sent in formalin.

The biopsy is done from various tissues like:

1. 1. Bone marrow for hematological diseases.
   2. Breast tissue for benign and malignant diseases.
   3. Endometrial tissue.
   4. Esophageal tissue for gastroesophageal reflux disease.
   5. Small intestine for gluten-sensitive enteropathy.
   6. Kidney for glomerular disease, and lupus nephritis.
   7. Liver for cirrhosis, hemochromatosis, and fever of undetermined origin.
   8. Lung biopsy.
   9. Pleural biopsy.

Liver biopsies for dry copper and iron weight:

1. 1. Specimens for dry copper or dry iron weight are required to be sent dry. Please do not place the specimen in formalin as this will invalidate the result.

Skin biopsy for Hansen’s disease:

1. 1. Select the most active margin of the most active lesion.
   2. Obtain a full-thickness biopsy including the subcutaneous fat.
   3. Either elliptical or punch biopsy is OK (4 mm punch is sufficient).
   4. Send in 10% neutral buffered formalin

Muscle biopsy:

1. 1. The muscle biopsy sample is immediately divided.
      1. One portion remains unfixed.
      2. while smaller portions are placed into formalin and glutaraldehyde fixatives.
      3. Fix the tissue on the card so that muscles should remain straight.
   2. The specimens are then sent to the laboratory for specialized processing and interpretation.
   3. Routine evaluation of the muscle biopsy sample involves the examination of formalin-fixed, paraffin processed sections.
   4. Unfixed frozen sections with standard histological and enzyme histochemical stains at the light microscopic level.
   5. Immunohistochemical stains are utilized for the diagnosis of various muscular dystrophies.
   6. Electron microscopic examination of the glutaraldehyde-fixed portion of the biopsy is performed when the light microscopic studies are inconclusive.

Kidney biopsy:

1. 1. These are done with the help of a needle.
   2. The material is sent in formalin.
   3. Special stains and immunochemistry are done for the diagnosis of various types of renal diseases.

Bone marrow biopsy:

1. 1. Aspiration bone marrow is done with a wide-bore needle.
   2. Trephine biopsy is the real bone tissue that is taken.

Testicular biopsy:  This may be:

1. 1. An open biopsy is to take surgical tissue from the testes.
   2. A punch biopsy may be taken when there is small tissue is needed.
   3. FNA  is done with a fine needle of 23 or 25 gauge.

Spleen biopsy: This can be taken:

1. 1. FNA can be done.
   2. 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:

1. 1. FNA can be done.
   2. Open lymph node biopsy gives better appreciation.

Cervical biopsy:  Cervical tissue is taken by curettage or by scraping and made the smear.

• Note see more details in surgical pathology part 1.

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