Introduction to Pathology

Study Notes

Pathology is an ancient discipline aimed at understanding the causes and mechanisms of diseases.
Key figures include Hippocrates, Avicenna (İbn Sina), Morgagni, and Virchow, who contributed significantly to the field.

Diseases can be congenital or acquired and can have known or unknown etiologies.
They may involve single or multiple causative factors and can damage normal cellular and tissue structures, leading to visible macroscopic or microscopic changes.
The outcome can range from healing to death.

The term "pathology" derives from “pathos” (suffering) and “logia” (study), signifying the study of disease.

Etiology (Causes of Diseases):
- Can be congenital or acquired.
- Factors may include biological agents (e.g., bacteria, viruses), physical agents (e.g., trauma, burns), chemical agents (e.g., poisons, alcohol), genetic factors, and idiopathic causes (unknown origins).
Pathogenesis (Mechanisms of Disease):
- Refers to how diseases develop, starting from exposure to precipitating agents through to the disease's manifestation.
Morphology (Structural Changes):
- Structural alterations can be observed at different levels: macroscopic (naked eye), microscopic (light microscope), and ultrastructural (electron microscope).
Clinical Significance:
- Pathology evaluates functional deficits linked to prognosis, like the relationship between chronic hepatitis activity and cirrhosis risk.
- Terms like morbidity (disease state) and mortality (death rate) are key in this evaluation.

Histopathology:
- Involves examination of tissues processed for microscopic evaluation to identify diseases, such as tumors.
Cytopathology:
- Focuses on the study of cells from tissues or body fluids, offering a simpler, cost-effective diagnostic approach.
Molecular Pathology:
- Involves analyzing molecular changes in tissues for disease diagnosis and understanding.

Diagnosis:
- Confirm diagnoses through analysis of specimens, such as biopsies for gastritis or malignancy.
Guidance of Treatment:
- Determine treatment paths (e.g., surgery) based on whether findings are benign or malignant and assess treatment effectiveness.
Screening Programs:
- Conduct population screenings to detect diseases early, such as PAP smear tests for cervical cancer, reducing morbidity and mortality rates.
Autopsy:
- Perform post-mortem examinations to ascertain causes of death, a vital aspect in forensic pathology.

Collection of Pathological Specimens:
- Obtain samples from biopsies, surgical procedures, autopsies, cytological examination, or frozen sections.

Small tissue samples collected for diagnostics include:
- Excisional and incisional biopsies.
- Needle biopsies for various organs (e.g., thyroid, liver).
- Curettage for endometrium or bone.

Surgical specimens are analyzed macroscopically and microscopically to identify abnormalities.

Cervical Smears:
- Capture cell samples to detect pre-cancerous lesions; essential for cancer screening.
Techniques include exfoliative cytology (cell shedding), lavage cytology (pressure application), and fine needle aspiration cytology.

Rapid pathological diagnosis during surgery when unexpected lesions must be evaluated quickly.

Tissue infiltrated with paraffin is placed in molds to solidify and is cut into thin slices (4-5 microns) using a microtome.

Standard staining includes Hematoxylin and Eosin (H&E), while advanced methods encompass histochemical and immunohistochemical staining.

Different microscopy techniques used include light microscopy, immunofluorescence, electron microscopy, and polarized light microscopy.

The oral mucosa is composed of stratified squamous nonkeratinized epithelium, with underlying connective and submucosal tissues, providing protection and nourishment.

Pathology also involves maintaining patient reports and archiving specimens for future reference, including slides, blocks, and diagnostic reports.

Pathologists and clinicians work collaboratively, complementing and trusting each other’s skills and findings for better patient care.

Ensure proper handling, labeling, and sufficient fixation of samples to avoid rejection in pathology labs.
Important information must be included on sample forms, such as clinical details, lesion location, and physician contact information.