Histopathology is one of the pillars of the contemporary medicine, a field, where biology, medicine, and art merge under the microscope. Scientific study of structural and functional defects in cells, tissues, and organs caused by disease is called pathophysiology. Histopathologists make the definitive diagnosis of countless diseases, predominantly cancer, based on the examination of thin sections of tissue in order to guide critical decisions in treatment and prognostication.

What is Histopathology? Defining the Discipline

Histopathology (Greek word: histos – tissue, pathos – disease, logos – study) is a sub-specialty of pathology that is the study of the expression of disease in biologically stained tissue sections prepared using a microscope. It is the morphological validation of a clinical suspicion.

The basic aim is to identify disease, mainly though not necessarily neoplasia (benign and malignant tumor’s) by determining:

• Architectural Disarray: Loss of the normal tissue organization.
• Cellular Atypia: Prominent dysplasia of cells in terms of cell size, shape, and staining characteristics (ex: hyperchromasia, pleomorphism).
• Mitotic Activity: elevated and disrupted cell division numbers.
• Invasiveness: Cells may be found to have broken through normal tissue boundaries.

From Patient to Pathologist: The Biopsy Journey

What is Biopsy ?

A biopsy is a diagnostic medical practice that involves the removal of a sample of cells or tissues in a living organism in order to identify the presence, cause, or extent of any disease in that particular organism under a microscope.

Methods of Collection

1. By Biopsy Technique:

• Incisional Biopsy Sample: A fragment or a slit of a big lesion or organ. It is gathered when it is not possible and practicable to remove the whole lesion. It is purely for diagnosis.
• Excisional Biopsy Sample: The entire lesion and usually a rim of normal tissue. It is typical of smaller skin lumps or masses and has both diagnostic and therapeutic uses.
• Punch Biopsy Sample: This is a core sample of a tissue that is cylindrical in form and is taken with a circular blade. Commonly used for: Skin lesions Uterine cervix Oral cavity Esophagus, stomach and intestine (through endoscopy), Bronchus (via bronchoscopy)
• Core Needle Biopsy Sample: A tissue core is a cylindric piece of tissue that is taken with a special wide-bore needle. It is a percutaneous (through the skin) sampling technique used to sample internal organs such as: Liver, Kidney, Breast, Prostate and Thyroid
• Curettage Biopsy Sample: Sample taken by scraping or scooping. The most common sample is: Endometrial curetting’s of the uterine lining to determine causes of abnormal bleeding.

2. By Type of Surgical Specimen:

These are mostly bigger samples that are taken out in surgery.

• Solid Organs or Masses: Whole organs or big parts of them. Examples: Uterus, spleen, kidney, lung lobe or a large tumor (e.g. of the colon, a breast tumor, or soft tissue tumor).
• Hollow Viscera: Organs and hollow tubes. Examples A piece of colon, small intestine, stomach, or appendix.
• Special Specimens:
  • Skin: Ellipses, or extensive resection.
  • Bone: Fractured limbs (e.g. by trauma or disease) or bone tumor.
  • Breast: Lumpectomies or mastectomies.
  • Lymph Nodes: Groups or single.

When a specimen is acquired, it should be conveyed in a proper way to avoid deterioration. It must be immobilized at once in a sufficient amount of fixative, usually 10 per cent formal saline, in a jar at least 10 times the bulk of the tissue. Labeling should be done properly in accordance with the request form.

The Histopathological Workflow: From Biopsy to Diagnosis

What is Histotechnique?

Histotechnique (also called histologic technique or micro-technique) is a term describing the whole collection of standardized techniques and protocols adopted to make biological tissues accessible to microscopy. The aim is to create a thin stained tissue section on a glass slide such that the cellular structures are maintained, visible and as similar to their living condition as possible.

The Step-by-Step Process of Histotechnique

1. Documentation:

Each sample is assigned the histopathology [HP] number that is written on the top right side. of the request slip, in a given record register and on the top of container.

2. Fixation:

It is the fixation of the constituents of cells, both physically and to a certain extent also. state, such that they will be resistant to successive treatment with diverse reagents with at least decay, or disintegration. This is done by exposing the tissue to chemical. compounds called fixatives.

3. Gross Examination:

The specimen is studied grossly through observing anatomical characteristics of the specimen. Representative sections are chosen to undergo additional procedures and small biopsies are chosen as a unit.

4. Decalcification:

Calcium salts are eliminated in the bony tissue in the event of a calcified tissue (bone). It is done before gross examination.

5. Tissue Processing:

It includes several steps whereby chosen sections of tissue are pumped through a. length of a series of chemicals. At this step tissues are saturated with a hardening. medium in which to section it fine. There are four stages involved:

• Completion of Fixation
• Dehydration
• Dealcoholization or Clearing.
• Impregnation or Infiltration6

6. Embedding:

In this step all processed tissues are blocked in a solidifying medium (e.g. paraffin). wax) used during the stage of impregnation.

7. Sectioning:

Sections of tissues are then cut using a machine known as Microtome. The produced sections can transmit light and are at a micron level. thickness.

8. Staining:

To examine tissue sections, tissue sections are selected on slides and staining is done. various cellular structures of tissue.

9. Mounting:

Each section is covered with cover slip with proper medium to acquire permanent. preparation for microscope

What is So Important About Histotechnique?

The whole practice of anatomic pathology and biomedical investigation depends on the quality of this method.

• Diagnosis: There are possibilities of artifact, distortion, or false staining that will cause a misdiagnosis of a tissue sample that has not been properly processed.
• Research: In scientific research strong sections are required to be analyzed correctly.
• Quality Control: The quality of slides produced must be diagnostically useful, and this cannot be achieved without meticulous attention to detail, time and the quality of reagents used at each stage.