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Introduction to pathology

La-or Chompuk, M.D. Department of pathology Naresuan University

Pathology: พยาธิวิทยา

• Greek: pathos, "feeling, suffering"; and logos, "the study of". • is the study and diagnosis of disease • is the study of the patterns, causes, mechanisms and effects of illness (disease) • is the basis of clinical laboratory medicine

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Basic studies in pathology

• Pathology is best learnt in two stages:

1. General pathology: 2. Systemic pathology:

General pathology

• is a broad and complex scientific field which seeks to understand the mechanisms of injury to cells and tissues, as well as responding to and repairing injury • Areas of study include cellular adaptation to injury, necrosis, inflammation, wound healing, and neoplasia.

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Systemic pathology

• is a study of systemic change in the diseases divided in organ systems. • CVS, CNS, respiratory, GI, hepatobiliary, KUB, genital, musculoskeletal, hematopathology, endocrine etc.

• Characterisitcs of disease: – cause/etiology – mechanisms of development (pathogenesis) – structural and functional features of diseases (pathological and clinical manifestation) – secondary effect (complications and sequelae) – prognosis – treatment – epidemiology

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Aetiology/causes

• Entirely genetic • Multifactorial (genetic and environmental factors) • Entirely environmental; infective agents, chemicals, radiation, mechanical trauma

Aetiology • Primary – Essential, idiopathic, spontaneous, cryptogenic e.g. primary HT – Initial stage: primary tumor e.g. lung cancer • Secondary – Disease represents a complication or manifestation of some underlying lesion e.g. secondary HT from renal a. stenosis – Subsequent stage: primary tumor disseminate to cause secondary tumor elsewhere e.g. lung cancer >> liver metastasis

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General classification of disease

• Congenital • Acquried – Genetic – Inflammation/infection – Non-genetic – Trauma – Tumor – Metabolism – Immune – Hemodynamic – Degenerative – Iatrogenic; induced by medical practioner’s words or actions

Pathogenesis/ mechanism

• Inflammation: a response to microorganisms and others harmful agents causing tissue injury • Degeneration: a deterioration of cells or tissues • Immune reaction: undesirable effects of the body’s immune system

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Structural and functional manifestations

• Symptom (อาการ) : the complaints of a patient • Signs (อาการแสดง): the abnormalities found on examination • Lesions (รอยโรค): the abnormal features • Pathognomonic abnormalities: specifically characteristic of a disease; Reed- Sternberg cells in Hodgkin’s disease

Structural abnormalities

• Space-occupying lesion (e.g. tumor) – destroying, compressing normal tissues • Deposition of an excessive or abnormal material in organs e.g. amyloid • Obstruction to normal flow within tube e.g. asthma, vascular obstruction • Rupture of a hollow viscus e.g. aneurysm, intestinal perforation

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Functional abnormalities

• Excessive secretion of a cell product e.g. nasal mucous in common cold • Insufficient secretion of a cell product e.g. insulin lack in diabetes mellitus • Impaired nerve conduction • Impaired contractility of a muscular structure

Complications/ sequelae

• Urinary tract infection >> sepsis • Burn >> scar contracture • Colon cancer >> lung metastasis • Pharyngitis >> post streptococcal glomerulonephritis • Encephalitis >> deafness

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Prognosis • Course of the disease, the fate of the patient e.g. - The 5-year survival prospects for carcinoma of the lung are about 5% - Lung cancer >> spread to liver, bone, brain >> has 6-month survival prospect • Remission: the process of conversion from active disease to quiescence • Relapse: signs and symptoms reappear

Characteristic of diseases; e.g.

Boil Lung cancer Cirrhosis Hypertension

Etiology S. aureus Smoking HBV ??

Pathogenesis Acute Genetic Imm - react Renin inflammation mutation

Manifestation Boil tumor cirrhosis High BP

Sequelae Septicemia metastasis Liver failure ICH

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Pathology disciplines (American)

• Anatomical pathology • Clinical pathology • Special pathology; – Forensic pathology – Molecular pathology

Pathology disciplines (British)

• Histopathology • Hematology • Chemical pathology • Microbiology • Immunopathology • Molecular pathology • Forensic pathology

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Anatomical pathology

• Deals with the tissue diagnosis of disease • Terminology – Biopsy; excision, incision – Necropsy, Autopsy – Fine needle aspiration (FNA) – Needle biopsy – Paracentesis – Thoracocentesis

Anatomical pathology

• Surgical pathology: – diagnosis of these specimens • Biopsy, Necropsy, Frozen section, Cytology • Autopsy – Special lab: • Special stains: AFB, GMS, PAS, Mucin • Immunohistochemical study (IHC): ER, PR, Her-2 • Immunofluoresence (IF): kidney disease • Electron microscope (EM) • Tissue microarray • Molecular lab: K-RAS mutation

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Tissue fixation ƒ10% neutral buffered formalin: routine H&E, IHC, PCR from paraffin block ƒ Bone: decalcification with EDTA, nitric acid ƒ Alcohol and acetone: good penetration, better preserve cytoplasmic enzyme, expensive ƒ Glutaraldehyde: electron microscope ƒVolume 10x of specimen

Containers

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Small-sized tissue

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Large-sized tissue

- Bisect with remaining normal orientation

Special orientation/margin specimen

ƒ Label with silk/ ink ƒ Diagram with label

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ขอมูลที่จําเปนเพิ่มเติม

Bone marrow CBC BM aspiration Flow cytometry

Bone and soft tissue Radiologic findings

Brain Radiologic findings

Surgical pathology

• Register • Cutting up/ gross examination • Embedding • Sectioning • Staining; Hematoxylin & Eosin stain (H&E) • Mounting • Analyse • Report

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H & E stain

Special lab in surgical pathology

• Special stains • Immunohistochemical studies (IHC) • Immunofluoresence (IF): need fresh tissue • In situ hybridization: FISH, SISH, CISH • Tissue microarray • Electron microscope (EM); special fixation; 1% glutaraldehyde, osmium tetroxide

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H&E H&E

H&E PAS; mucormycosis

H&E AFB stain

H&E GMS stain

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IHC; CD34 IHC; CK

IF; Bullous pemphigoid IF; MGN, IgG

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FISH

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Tissue microarray

• consist of paraffin blocks in which up to 1000 separate tissue cores are assembled in array fashion to allow multiplex histological analysis

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Tissue microarray

TEM; HHV-6 SEM; glomerulus; podocyte

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Cytopathology

– Body fluid • ascites, CSF, pleural fluid, pericardial fluid • Fixation: non, cytolite, 4oC – FNA & Smear: fix in 95% ethyl alcohol – Fine needle aspiration (FNA); thyroid, breast, LN – Smear; nipple smear – Pap smear; cervical cancer screening • Conventional • Liquid base preparation – Cell block

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Collection of fluid cytology

Routine centrifuge

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Cytocentrifuge

Cytocentrifuge

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Cytoblock/ cell block

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Pap smear: conventional

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Autopsy

• Determining the cause of death • Audit the accuracy of clinical diagnosis • Education of undergraduates and postgraduates • Research into the causes and mechanisms of disease • Gathering accurate statistics about disease incidence

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ตรวจแลวอยางถี่ถวน รักษาแลวอยางเต็มที่ บางทียังเอาชนะโรคไมได ขั้นสุดทายจึงตองตรวจศพ เพื่อใหรูแนนอน เอาไวเปนความรู เทียบเคียงกับอาการและการรักษาที่แลวมา สําหรับชวยชีวิตคนอื่นตอไป

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ญาติสายตรงผูมีสิทธิ์อนุญาตใหผาตรวจศพ เรียงตามลําดับดังนี้ 1) คูสมรสที่ถูกตองตามกฎหมาย 2) บุตรที่บรรลุนิติภาวะ 3) บิดา มารดา 4) พี่ นองรวมบิดามารดาเดียวกันที่บรรลุนิติภาวะ 5) พี่ นองรวมบิดาหรือมารดาเดียวกันที่บรรลุนิติภาวะ 6) ปู ยา ตา ยาย 7) ลุง ปา นา อา หมายเหตุ ผูดูแล ผูอุปการะ นายจาง หรือผูอํานวยการโรงพยาบาล ไมมีสิทธิ์ อนุญาตใหตรวจศพ (ยกเวนบางกรณี)

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Clinical pathology

• Deals with the laboratory analysis of blood, urine an other body fluids, using the tools of chemistry, microbiology, hematology and molecular pathology

• Work with medical technologists, hospital administrations, and referring physicians to ensure the accuracy and optimal utilization of laboratory testing.

Clinical pathology

• Hematology; CBC, Hb typing etc. • Microbiology; culture • Immunology; Ag-Ab, ELISA, agglutination • Microscopy; Urine analysis, stool analysis • Chemistry; FBS, lipid profile • Molecular lab; DNA • Toxicology • Blood bank

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Special pathology

• General pathology; a pathologists practice both anatomical and clinical pathology

• Molecular pathology is an emerging discipline within pathology, and focuses on the study and diagnosis of disease through the examination of molecules within organs, tissues or body fluid

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Forensic pathology • is the subspecialty of pathology that focuses on medicolegal investigations of sudden or unexpected death. • A consultant in medicolegal cases in OPD/IPD such as rape, homicide, suicide • visit crime scenes or accidents • to testify in court • Lab: toxicology, DNA, x-ray

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Pathologists duties

• work with other doctors,or medical team • to set guidelines and standards for medical laboratory testing that help improve a patient's medical care and guide treatment • ensure the quality and safety of medical laboratories. •lecturer

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References

• ตําราเรียนพยาธิวิทยาทั่วไป ภาควิชาพยาธิวิทยาและนิติเวชศาสตร คณะ แพทยศาสตร มหาวิทยาลัยนเรศวร 2551. • Robbins and Cotran Pathologic Basis of Disease. 8th ed, Philadelphia, Elsevier Saunders, 2010. • JCE Underwood. General and Systemic pathology, 3rd ed. Churchill Livingstone. 2000.

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