Introduction to Pathology

Introduction to Pathology

• 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.

Understanding Disease

• 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.

Definition of Pathology

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

Components of Pathology

• 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.

Categories of Pathology

• 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.

Role of Pathologists

• 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.

Routine Laboratory Procedures

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

Types of Biopsies

• 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.

Evaluation of Surgical Samples

• Surgical specimens are analyzed macroscopically and microscopically to identify abnormalities.

Cytological Sampling Techniques

• 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.

Frozen Section and Intraoperative Consultation

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

Tissue Processing Steps

• Dehydration: Remove water from tissue samples using alcohol.
• Clearing: Replace alcohol with xylene to prevent fragility.
• Infiltration: Use paraffin to prepare tissue for slicing.

Embedding and Sectioning

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

Staining Techniques

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

Microscopy

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

Oral Mucosa Structure

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

Administrative Aspects

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

Collaboration in Healthcare

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

Sample Rejection Criteria

• 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.

Explore the fundamentals of pathology, including the historical figures who shaped the discipline. Understand the causes and mechanisms of diseases, their classification, and the implications of disease processes. This quiz will help you grasp essential concepts in pathology.