ROLE OF HISTOPATHOLOGY IN LAB SERVICES
Histopathology is the study of tissues under the microscope to diagnose diseases, particularly cancers and other abnormal tissue conditions. It is a crucial part of pathology, focusing on the microscopic examination of tissue samples (biopsies) to detect abnormalities.
Basics of Histopathology:
1. Tissue Sampling:
Either a small piece of tissue or whole organ or part of lesion from the organ for eg breast,lymph nodes,kidney, thyroid etc is being removed from the body, typically during surgery or biopsy procedures.
Samples can come from any organ or part of the body.
2. Fixation:
The tissue sample is preserved in formalin (formaldehyde solution) or any other special fixative depending on the site of biopsy to prevent decay and maintain its structure for analysis.
This process is essential to maintain the tissue’s integrity.
3. Tissue Processing:
The fixed tissue is dehydrated in a systematic manner using alcohol. Tissue processing in histopathology is the preparation of tissue samples for microscopic examination. It involves several steps like dehydartion, clearing embedding, sectioning, staining and mounting .These steps ensure that the tissue is adequately preserved and sectioned for analysis.
The Processing can be done manually or automated.
The tissue sections are stained to differentiate cellular components.
The most common stain is Hematoxylin and Eosin (H&E):
Hematoxylin stains the cell nuclei blue.
Eosin stains the cytoplasm and extracellular matrix pink.
Other special stains or immunohistochemical techniques may be used depending on the diagnostic needs.
The slides are then ready for microscopic examination.
5. Microscopic Examination:
The trained histopathologist diagnose the diseases such as cancer, inflammation, fibrosis, infections or other signs of disease based on the abnormalities or specific features on microscopic examination of the stained tissue slides.
The histo-pathologist also may take help of special stains or ancillary techniques like immunohistochemistry or molecular studies to confirm the diagnosis.
Proper clinical history and radiology is helpful for a histopathologist in rendering accurate diagnosis which in turn is very important in the treatment.
The histopathologist :
1.Provide detailed diagnostic reports that guide the treatment decisions made by clinicians and surgeons.
2.To diagnose the type of disease for eg. inflammatory, neoplastic, infectious etc.
3.Determine the type, grade, and stage of diseases, especially cancers, which is critical for determining prognosis and treatment strategies (e.g., chemotherapy, surgery, radiotherapy etc).
4. Intraoperative Consultations (Frozen section):
Frozen section is a rapid histopathological technique used during surgeries to provide immediate diagnostic information. It is often employed when quick and critical decisions are required by surgeon for eg extent and nature of surgery.
Uses of Frozen Section:
Intraoperative diagnosis: Frozen sections are used during surgery to assess the nature of a mass, whether malignant or benign based on which further surgery is decided.
Margin assessment: Surgeons use frozen sections to check if tumor margins are free of cancer cells, ensuring complete removal of the tumor.
Lymph node evaluation: It can be used to evaluate lymph nodes during cancer surgeries to determine if cancer has spread or not and to decide further the extent of surgery.
5. Specialized Techniques:
Perform and interpret advanced diagnostic tests such as Immunohistochemistry (IHC), Fluorescence In Situ Hybridization (FISH), and molecular diagnostics (e.g., gene mutations).
These techniques besides helping in accuarte diagnosis and prognosis also aids in identifying specific biomarkers that can influence treatment (e.g., hormone receptor status in breast cancer).
6. Collaborating with Clinicians:
Histopathologists work in multidisciplinary teams (MDTs) with surgeons, oncologists, radiologists, and other medical professionals to discuss complex cases and treatment plans.
Their input is crucial in deciding the best course of action for patient care.
7. Research and Teaching:
Some histopathologists are involved in research to develop better diagnostic techniques or study the pathology of diseases in depth.
They may also teach medical students, residents, and laboratory staff.
Histopathologists primarily work in laboratories and hospitals. Their job is behind the scenes but is vital for accurate diagnosis and treatment planning in medicine, particularly in oncology.
In summary, histopathologists are essential for diagnosing diseases by interpreting tissue samples, working with clinical teams, and contributing to patient care through their diagnostic expertise.
Dr Lovy Agarwal
Consultant Histopathologist