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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

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 fieldwhich 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

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– Genetic– Non-genetic

• Acquried– Inflammation/infection– 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

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

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 inflammation

Genetic mutation

Imm - react Renin

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

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 fixation10% neutral buffered formalin: routine H&E,

IHC, PCR from paraffin block

Bone: decalcification with EDTA, nitric acid

Alcohol and acetone: good penetration, better

preserve cytoplasmic enzyme, expensive

Glutaraldehyde: electron microscope

Volume 10x of specimen

ContainersSmall-sized tissue

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Large-sized tissue

- Bisect with remaining normal orientation

Special orientation/margin specimen

Label with silk/ ink

Diagram with label

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ขอมูลที่จําเปนเพิ่มเติม

Bone marrow CBCBM aspirationFlow cytometry

Bone and soft tissueRadiologic findings

BrainRadiologic 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

PAS; mucormycosis

H&E H&E

H&E

AFB stain

GMS stain

H&E

H&E

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IF; Bullous pemphigoid

IHC; CD34

IF; MGN, IgG

IHC; CK

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FISH

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-6SEM; glomerulus; podocyte

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

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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ตรวจแลวอยางถี่ถวน รักษาแลวอยางเต็มที่

บางทียังเอาชนะโรคไมได

ขั้นสุดทายจึงตองตรวจศพ

เพื่อใหรูแนนอน เอาไวเปนความรู

เทียบเคียงกับอาการและการรักษาที่แลวมา

สําหรับชวยชีวิตคนอื่นตอไป

ญาติสายตรงผูมีสิทธิ์อนุญาตใหผาตรวจศพ เรียงตามลําดับดังนี้

1) คูสมรสที่ถูกตองตามกฎหมาย2) บุตรที่บรรลุนิติภาวะ3) บิดา มารดา4) พี่ นองรวมบิดามารดาเดียวกันที่บรรลุนิติภาวะ

5) พี่ นองรวมบิดาหรือมารดาเดียวกันที่บรรลุนิติภาวะ

6) ปู ยา ตา ยาย7) ลุง ปา นา อา

หมายเหตุ ผูดูแล ผูอุปการะ นายจาง หรือผูอํานวยการโรงพยาบาล ไมมีสิทธิ์

อนุญาตใหตรวจศพ (ยกเวนบางกรณี)

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Clinical pathology

• Deals with the laboratory analysis of blood, urinean 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

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

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.