Histopathology PDF

MODULE 05: SECTIONS OF THE CLINICAL LABORATORY – PART 2 MODULE OBJECTIVES 1) Describe the Microbiology section and enumerate the routine tests carried out inside the Microbiology section. 2) Enumerate the various classes of medically important parasites and the role of the Parasitology sec...

MODULE 05: SECTIONS OF THE CLINICAL LABORATORY – PART 2 MODULE OBJECTIVES 1) Describe the Microbiology section and enumerate the routine tests carried out inside the Microbiology section. 2) Enumerate the various classes of medically important parasites and the role of the Parasitology section for the detection of parasites in stool samples. 3) Describe the performance of physical, chemical, and microscopic examination during routine urinalysis. 4) Enumerate and define the steps of routine tissue processing in the Histopathology section. MODULE 05 – UNIT 04 THE HISTOPATHOLOGY SECTION UNIT OBJECTIVES 1) Identify figures that contributed to the development of histopathology. 2) Enumerate and define the steps of routine tissue processing in the Histopathology Section. 3) Define cytology and differentiate exfoliative cytology from aspiration cytology. TOPIC OUTLINE Nature of Histopathology Historical Developments Routine Services Routine Tissue Processing Cytology and Cytopathology M05 – U04 – TOPIC 01 The Nature of Histopathology  Histopathology Cytology Cancer diagnostics  Hyperplasia Dysplasia Metaplasia Anaplasia Identifies tumor grades and margins Normal Abnormal M05 – U02 – TOPIC 02 THE HISTORICAL DEVELOPMENT  Who is the father of which? Johannes Histologic Muller Pathology Marcello Modern Anatomic Malpighi Pathology Rudolf Microscopic Virchow Pathology  Who is the father of which? Johannes Histologic Muller Pathology Marcello Modern Anatomic Malphigi Pathology Rudolf Microscopic Virchow Pathology Johannes Muller Father of Histologic Pathology Elements of Physiology Systematic study of tissue structures Marcello Malphigi Father of Modern Anatomic Pathology Embryology, glandular physiology, and tissue preservation Heat fixation Rudolf Virchow Father of Microscopic Pathology First pathology laboratory Cellular study of diseases Ferdinand Blum Fixative effects of formaldehyde Modern day Formalin: standard tissue fixative Why do we have to dilute pure formaldehyde into formalin? Use of Formalin Stability and handling Controlled fixation Safety concerns Compatibility with tissue Invention of Microtomes Microtome micro = “small” tome = “cut” Key tool for cutting thin tissue sections  Tissue Blocks and ribbons Paraffin Wax Celloidin Sliding Microtome Adams Jr. Large, hard tissue specimens Serial sectioning Rocking Microtome Trefall Softer specimens Rapid sectioning Rotary Microtome Minot Consistent, thin sections Most widely used today Freezing Microtome Queckett Frozen tissue without embedding Rapid intraoperative diagnostics Cryostat Operates w/in a refrigerated chamber (-20°C to -30°C) Rapid diagnostics Enzyme histochemistry How can a cryostat preserve enzyme activity for enzyme histochemistry? Preserving Enzyme Activity Rapid freezing prevents denaturation Cold environment maintains enzyme stability Minimal chemical processing Ultrathin Microtome Ultra-thin sections (50–100 nm) Electron microscopy Subcellular structures  Type Inventor Key Feature Section Application Cuts large, hard Serial sectioning of hard Sliding Adams 6–15 µm tissues tissues (e.g., bone) Rocking motion for Soft tissues (e.g., liver, Rocking Trefall 10–20 µm rapid sectioning spleen) Rotary mechanism for Standard lab use for Rotary Minot 4–6 µm consistent thickness paraffin-embedded tissues Intraoperative diagnostics, Freezing Queckett Cuts frozen tissues 8–15 µm enzyme studies Refrigerated chamber Rapid diagnostics, Cryostat NA 5–10 µm for cryosections enzyme histochemistry Cuts ultrathin Ultrathin NA 50–100 nm Electron microscopy sections M05 – U04 – TOPIC 03 THE ROUTINE SERVICES Grossing Macroscopic evaluation Sectioning into smaller samples Placement into cassettes Who performs the grossing procedure?  Pathologists Complex specimens Tumors, organ resections, etc. Ensure diagnostically significant areas are sampled Document findings in gross reports  Pathology Assistants (PA) Trained professionals working under pathologist supervision Gross routine specimens Biopsies, gallbladders, appendices, etc. Follow established protocols  Histotechnologists Assist in small labs for routine or small specimens Operate under direct supervision of a pathologist Routine Tissue Processing Routine Tissue Processing 1. Fixation 5. Embedding 2. Dehydration 6. Trimming 3. Clearing 7. Sectioning 4. Infiltration/ 8. Staining Impregnation 9. Mounting Staining to Mounting Process Hydrate the section Apply the hematoxylin stain Complete the nuclear stain by “blueing” Remove excess background stain Apply the eosin counterstain Rinse, dehydrate, clear and mount Cytology and Cytopathology Diagnose or screen for cancer, infectious diseases, inflammatory conditions Exfoliative cytology Aspiration cytology Exfoliative Cytology Cells that are “Shed” by the body naturally Manually scraped or brushed (exfoliated) from the tissue surface Exfoliative Cytology Smear Technique Exfoliative Cytology Cell Block Technique Aspiration Cytology Specimens that do not shed cells spontaneously Fine Needle Aspiration Biopsy (FNAB) Exfoliative Cytology Smear FNAB Smear Cytological Procedures CSF analysis Cytology of ovarian fluid Pleural fluid analysis Brochoalveolar lavage Peritoneal/ascitic fluid (BAL) analysis Urine cytology Pericardial fluid analysis Sputum cytology Synovial fluid analysis Nasal fluid cytology Cyst fluid analysis Gastric fluid/lavage Cytology of nipple analysis discharge Gynecological cytology Gynecological Cytology Papanicolau stain Pap Smear Dr. George Papanicolau  Pap Smear Speculum Ayre spatula Pap Smear Pap Smear Hematoxylin stain → Orange stain → Eosin Azure Eosin Azure: Eosin Y + Light Green SF + Bismarck Brown Y Microscopic Evaluation Normal Abnormal QUESTIONS & CLARIFICATIONS