CLASE TEÓRICA 1 - INTRODUCCIÓN A LA PATOLOGÍA

Introduction to Pathology and Laboratory Techniques

Overview of Pathological Methods

• Gabriela Asís introduces the theoretical activity focusing on general aspects of pathology and anatomical pathology laboratory methods.

• The primary study methods in anatomical pathology include autopsies, surgical pathology (biopsies and surgical specimens), and cytology, supplemented by special studies like electron microscopy, immunohistochemistry, immunofluorescence, and molecular biology.

Material Fixation Techniques

• Emphasis on the importance of proper fixation for materials obtained from surgery; biopsies and surgical pieces are fixed in 10% formalin while cytologies are fixed in 95% alcohol.

• Specific fixation techniques for various samples: sputum is preserved in 50% alcohol; organic liquids such as pleural fluid or abdominal cavity fluid are also fixed in 50% alcohol; urine is fixed in 95% alcohol.

Understanding Surgical Specimens

Case Study: Colectomy Specimen

• Presentation of a colectomy specimen showing an irregular elevated lesion potentially indicative of a malignant tumor.

Endoscopic Biopsy Technique

• Description of endoscopy using an endoscope equipped with a device for obtaining biopsy samples; both types of material (colectomy specimen and biopsy) are fixed in formalin.

Processing Biological Samples

Urine Fixation Insights

• Clarification that urine is a liquid medium requiring fixation with 95% alcohol despite being diluted when mixed with other substances.

Slide Preparation for Microscopy

• Explanation of slide preparation through extending materials onto slides for microscopic observation after processing.

Staining Techniques in Histopathology

Routine Staining Procedures

• Most anatomical pathology labs utilize automatic processors followed by routine staining techniques like hematoxylin-eosin (H&E).

Special Stains for Lipids and Enzymes

• Discussion on specialized staining techniques to demonstrate enzymes or lipids within tissues, highlighting the need for different processing methods when dealing with lipid-rich tissues.

Identifying Pathological Changes

Hepatic Tissue Analysis

• Examination of histological cuts showing hepatic parenchyma occupied by vacuoles characteristic of liver disease; special stains required to confirm fat presence due to lipid loss during processing.

Renal Pathology Visualization

• Presentation of renal histological sections stained with periodic acid-Schiff (PAS), which highlights glomerular structures and can indicate pathological changes like thickening membranes.

Immunohistochemistry Applications

Importance in Tumor Diagnosis

• Immunohistochemistry serves as a crucial diagnostic tool for identifying malignant tumors, especially those with unknown origins or undifferentiated characteristics.

Detection Mechanism

• The technique relies on antibodies linked to peroxidases to detect antigens present on cell surfaces or within cells' nuclei.

Immunohistochemical Markers and Biopsy Techniques

Overview of Immunohistochemical Techniques

• The use of flow cytometry is highlighted for quantifying chemical components in cells, alongside autoradiography to detect radioactive isotopes in tissues.

• Transmission electron microscopy is emphasized for renal biopsies, tumor studies, and diagnosing viral diseases.

Types of Biopsies

• Surgical pathology includes biopsies and surgical specimens; a biopsy is defined as a tissue fragment extracted from a living organism for analysis.

• Intraoperative or frozen biopsy provides rapid diagnostic feedback during surgery, allowing surgeons to make informed decisions on proceeding with the operation.

• Excisional biopsy removes an entire lesion (e.g., a mole), while incisional biopsy only samples part of a lesion, such as a tumor fragment.

Specialized Biopsy Techniques

• Puncture biopsies utilize thicker needles to extract cylindrical tissue samples from organs like the liver and kidney; fine needle aspiration (FNA) is common for thyroid lesions.

• Endoscopic biopsies are performed using an endoscope to obtain small tissue samples from tubular organs.

Applications of Intraoperative Biopsy

• Intraoperative frozen biopsies are routinely used in breast surgeries to assess metastasis in axillary lymph nodes and other oncological procedures.

Renal Biopsy Insights

• Renal puncture biopsy involves extracting cylindrical tissue samples; adequate glomerular representation is crucial for accurate histopathological diagnosis.

Advanced Diagnostic Techniques

• Immunofluorescence microscopy aids in diagnosing immunological disorders by visualizing antigen-antibody complexes deposited in tissues.

• Electron microscopy reveals cellular anomalies, including deposits near glomerular membranes that may indicate renal dysfunction.

Tumor Types and Diagnostic Techniques in Pathology

Common Skin Tumors and Surgical Techniques

• Discussion on the most common skin tumor, highlighting a conservative surgical approach with tumorectomy or quadrantectomy in breast tissue.

• Description of a tumor with poorly defined borders, characterized by a whitish color and likely hard consistency, indicating potential malignancy.

Benign Ovarian Tumors

• Introduction to cystadenoma of the ovary as a benign tumor originating from ovarian epithelial cells; "cyst" refers to its fluid-filled nature.

• Explanation of the internal structure of such tumors, emphasizing the presence of a large cavity filled with serous fluid.

Cytodiagnostic Methods

• Overview of cytodiagnosis through exfoliative cytology, particularly focusing on cervical epithelium analysis for hormonal influence and early anomaly detection.

• Importance of early detection in identifying dysplastic changes or carcinoma through cytological studies.

Bronchial Epithelium Analysis

• Mention of bronchial epithelium study via bronchoscopy techniques for early diagnosis compared to histopathological methods.

• Use of specialized equipment like fibrobronchoscopy for obtaining samples from bronchial washings to diagnose diseases earlier.

Exfoliative Cytology Examples

• Application of cytological techniques to analyze effusions from serous cavities (e.g., peritoneal, pleural).

• Discussion on advanced techniques like molecular biology assays (PCR for DNA/RNA analysis).

Papanicolaou Test Insights

• Introduction to the Papanicolaou test as a method for examining exfoliated cervical cells; description includes normal cell characteristics.

• Identification of abnormal cells indicating HPV interaction, including multinucleated cells and signs of coilocytic changes.

Dysplasia Indicators and Carcinoma Risks

• Recognition that significant cellular alterations may indicate higher-grade dysplasia or potential carcinoma development linked to HPV infection.

• Observations on pleomorphic cell groups suggesting severe dysplastic changes warranting close monitoring.

Autopsy's Role in Pathology

• Definition and importance of autopsies as post-mortem anatomical pathology studies; emphasizes systematic examination across all organ systems.

Autopsies: Importance and Types

The Role of Autopsies in Medical Practice

• Discussion on the involvement of various medical professionals in understanding patient deaths, highlighting their concern for accurate diagnoses.

• Emphasis on the declining number of autopsies performed in contemporary medicine, stressing their significance as a vital study method.

• Differentiation between clinical autopsy (focused on disease study) and forensic autopsy (aimed at identifying deceased individuals and determining responsibility).

Clinical vs. Forensic Autopsies

• Clinical autopsies are requested by clinicians for academic purposes, while forensic autopsies are mandated by legal authorities.

• Forensic autopsies are crucial in cases of violent deaths such as suicides or homicides, emphasizing their judicial importance.

• Consent is often required for clinical autopsies from family members; however, forensic autopsies cannot be refused.

Educational Aspects of Pathology

• Clinical findings from autopsies can contribute to educational discussions in anatomical clinics versus legal presentations during trials.

• Introduction to congenital pathologies with an example of interventricular communication as a common condition observed during studies.

Metabolic and Inflammatory Diseases

• Diabetes is highlighted as a significant metabolic disorder affecting multiple organs, particularly the kidneys; its high morbidity and mortality rates are noted.

• Comparison made between diabetic glomerulosclerosis and amyloidosis through differential diagnosis techniques.

Vascular Disorders and Infections

• Presentation of hemorrhagic infarcts within brain tissue as examples of vascular disorders caused by vessel wall failures leading to life-threatening conditions.

• Examination of liver tissue under microscopy reveals inflammatory infiltrates indicative of hepatitis, showcasing how viral infections impact pathology studies.

Triquinosis and Tumor Pathology

Overview of Tumor Pathology

• Triquinosis is a significant chapter in pathological anatomy, focusing on tumor pathology which classifies tumors into malignant and benign types.

• The most common tumor found in the colon is adenocarcinoma, characterized by glandular structures that appear irregular and atypical under histopathological examination.

Characteristics of Malignant Tumors

• Microscopic sections reveal pleomorphism, indicating that cells within malignant tumors vary significantly in appearance.

• Anaplastic cells are typically present in malignant tumors; they exhibit large, irregular nuclei and altered nuclear-cytoplasmic ratios.

Understanding Disease Etiology

• It’s crucial to gather epidemiological data such as age, sex, lifestyle habits (e.g., smoking), and occupational exposure to understand disease etiology.

• The concept of pathogenesis refers to the sequence of events leading to cellular or tissue responses against etiological agents.

Pathogenesis Process

• The process begins with an initial stimulus (e.g., genetic mutation), leading to structural and functional alterations culminating in disease manifestation through signs and symptoms.

Practical Skills Development

• Students should develop skills for describing macroscopic specimens and histopathological preparations during practical sessions.

• Examples include normal versus atrophied kidneys; understanding these differences is essential for diagnosis.

Histopathological Insights

Liver Pathology Example

• A histopathological example from the liver shows hepatocyte trabeculae with evidence of cholestasis due to bile flow obstruction.

• Observations include brownish deposits indicating bile accumulation resulting from this obstruction.

Course Introduction and Expectations

Faculty Introduction

• The teaching team was introduced, emphasizing their commitment despite challenging circumstances like the pandemic.

Encouragement for Students