Lecture 1 Introduction To Pathology PDF

Lecture 1 Introduction to Pathology  Learning Objectives ▪ Define the term pathology ▪ Understand the term etiology ▪ Know the predisposing factors and classification of diseases ▪ Understand the pathogenesis of a disease ▪ Define the terms fate and complications ▪ Menti...

Lecture 1 Introduction to Pathology  Learning Objectives ▪ Define the term pathology ▪ Understand the term etiology ▪ Know the predisposing factors and classification of diseases ▪ Understand the pathogenesis of a disease ▪ Define the terms fate and complications ▪ Mention the components of the pathological picture of a disease ▪ Know how to study and why we study pathology ▪ Identify type of pathological specimens and how it is prepared and examined ▪ Understand the techniques used in the pathology lab. for diagnosis of diseases What is Pathology? Pathology is the science which deals with the study of disease process Pathos = suffering Logos = study  It is abridging discipline involving both basic science and clinical practice devoted to the study of the structural and functional changes in cells, tissues, and organs that underlie disease. Pathology attempts to explain why the signs and symptoms occur  Fundamental items of Pathologic study 1- Definition: Each disease has a definition E.g. An abscess is a localized suppurative inflammation 2- Etiology (causes): Classified as predisposing and determining or direct causes. 1- Predisposing factors brings the body under the influence of the direct cause. E.g. a small abrasion in the skin may predispose to the entry of organisms and abscess formation. 2-The direct causes may be exogenous (from outside the body) as bacteria, viruses and parasites. or endogenous (originates from the body itself) as autoimmune diseases.  Classification of Diseases Congenital Acquired - inflammatory - vascular - growth disorder - metabolic - degenerative - drug induced - infective  3- Pathogenesis of a disease: means the steps or mechanism of production of the lesion of that disease. 4- A lesion: Morphologic changes is the group of local changes in the structure and functions of a certain tissue or organ. Lesions are examined both grossly (by the naked eye) and microscopically (by the microscope).  *The gross description: includes changes in size, shape, colour, cut surface and consistency of the diseased organ. 5- Fate or outcome of the disease: Regression (good fate) Progression with complications (bad fate) Prognosis: The prediction of how the patient’s disease will progress  Sign = objective symptom of disease Ascites, cachexia, cough, dysphagia, organ enlargement as hepatomegaly, splenomegaly, etc….. Symptom = subjective sign of disease Chest pain, loss of appetite, weakness, numbness, headache, toothache ….etc Observation of gross specimen: a hypertrophic heart (left) and a normal heart (right)  Types of pathologic specimens 1- Biopsy: Specimen removed from a living patient in the operating room. 2- Diagnostic cytology: Examination of body fluids as effusions, sputum, urine, CSF. 3- Autopsy: Specimen removed from a dead body in the postmortem room.  1- CYTOLOGICAL DIAGNOSIS (Cytopathology): Def: Diagnosis of a disease by examination of isolated cells in body fluids Samples for cytological examination may be obtained by a variety of techniques: A- Exfoliated cells from a malignant tumour of the lung, urinary bladder or brain can be identified in samples of sputum, urine and CSF respectively. Also from body fluids as pleural effusion, ascitic fluid or pericardial effusion. Bone marrow smears for diagnosis of hematological malignancy and metastatic cancer. B- Wash : gastric wash bronchial wash can obtain cells exfoliated from gastric and bronchial cancer. C- Brushing or scraping of suspicious lesions that have been visualized by endoscopy (bronchoscopy, gastroscopy and colonoscopy). D- Fine needle aspiration smear for cancer thyroid, liver, pancreas, breast and lymph nodes obtained by the help of CT scan or ultrasonography. What to do with cytology, vaginal smear, FNA smears? Immediate smearing on glass slide with immediate fixation in ethyl alcohol 95% is mandatory.  2-HISTOPATHOLOGICAL DIAGNOSIS: Histological diagnosis is considered the definitive method to diagnose diseases by examination of the tissue removed by surgeons Types of biopsy specimens *Excisional biopsy: e.g. radical mastectomy, nephrectomy, total cystectomy, *Tru-cut needle biopsy: tissue sample of the neoplasm can be obtained by needle biopsy. *Incisional biopsy,*Punch biopsy can be obtained from tumours of the oral cavity, nose and rectum. *Endometrial curetting (D&C biopsy) for diagnosis of endometrial lesions as retained products of conception, irregular uterine bleeding *TUR specimens for urinary bladder and prostatic neoplasms (cystoscopy) * Endoscopic biopsy from the larynx, oesophagus, stomach, and colon (upper & lower endoscopy)  Techniques used in Pathology A- Frozen section: rapidly prepared from fresh specimens for distinguishing a malignant neoplasm from a benign one and in reporting about safety margins. B- Paraffin sections: Provide the best material for pathological diagnosis, prepared from the tissue and stained with Hematoxylin & Eosin stain. Special stains could be done on it. C- Immunoperoxidase technique (immunohistochemistry): Can be utilized for detection of cytoplasmic proteins, enzymes and hormones in tumor cells (tumor antigens), all represent tumor markers (biochemical indicators) of the presence of a tumor.  D- Serum Tumour markers: Tumor-derived or tumour-associated molecules that can be detected in blood or other body fluids. They are used to confirm diagnosis and determine the response to therapy. Examples: *Carcinoembryonic antigen (CEA) in G.I.T. and breast carcinoma. *Alpha-fetoprotein in hepatic carcinomas. *Prostatic acid phosphatase in prostatic carcinoma.  E- Electron microscopy: Ultrathin sections are prepared and examined for diagnosis of difficult types of diseases and cancer. F- Molecular diagnosis: -PCR (polymerase chain reaction) for diagnosis of leukemia. -Flow cytometry measure the DNA content of the tumor cells.  How pathological specimen is prepared and examined Fixation Put specimens in a suitable clean container Add fixative (what/ how much) Accurate labeling (patient name, hospital number, specimen parts, left and right, …etc)  Fixation Why fixative: preserve specimen from decay & autolysis Stabilise tissue integrity for histopathological examination. What fixative: Formaldehyde (formalin): 10% Alcohol for cytological smears  Day-1 Gross description & overnight fixation  Day-2 Taking representative sections (trimming) by pathologist.. how many sections are taken? It depends upon the specimen nature and size (1->20) Tissue processing to make sections hard and clear (Alcohols and xylene)  Paraffin embedding system Day-3 Microtome cuts blocks Embedding in paraffin to make paraffin block Cutting of paraffin blocks to make blank slides Staining paraffin blocks 448/201 0 Day-3 Staining of slides (Haematoxyline and Eosine are used in routine work) Preparation of slides for Pathologists to examine and write report  Day-4 Day-5 http://t1.gstatic.com/images?q=tbn:ANd9GcTlbrPuKKXOUZ3iVuBjSSGYmcGzqOHjwdYOoLy-ywl1  Objectives of Pathology Study (Why) 1- To describe the disease process to be able to correlate the clinical manifestations with the pathological changes that occurs in the diseased organ. 2- To predict the course and outcome (fate and prognosis) of various diseases. 3- To realize the role of histopathology and diagnostic cytology in the diagnosis and treatment of diseases. Be able to develop a correct diagnosis  MCQ 1-The observation of the pathological changes of organs or tissues by the naked eye is called A-experimental pathology B-gross pathology C-molecular pathology D-histopathology  MCQ 2-The diagnosis of disease by examination of isolated cells in body fluids is called: A-cytopathology B-Immunology C-histpoathology D-microbiology  MCQ 3-The steps or mechanisms of production of the lesion of a disease is termed: A-aetiology B-prognosis C-pathogenesis D- morphology  MCQ 4-The prediction of how a patient’s disease will progress is called: A-diagnosis B-pathogenesis C-aetiology D-prognosis  MCQ 6-The diagnosis of disease from the examination of tissue sections is called: A-hematology B-cytopathology C-immunology D-histopathology  MCQ 7-Which of the following is the study of disease processes? A-Microbiology B-Pathology C-Biochemistry D-Parasitology  MCQ 8-Which of the following is studying of predisposing factors and causes of disease? A-Disease etiology B-Disease prognosis C-Disease mechanism D-Disease treatment  MCQ 9-. Why tissues removed from the patient as a biopsy is fixed in 10% formalin? A. To prevent autolysis B. To stain cells C. To cause lysis D. For sterilization  MCQ 10-For frozen section, the tissue should be sent to the laboratory in which of the following forms? A. Fresh unfixed B. in 10% formalin C. Saline D. Alcohol  MCQ 11-Most diagnostic histopathology specimens are stained by which of the following stains? A-Heamatoxylin and eosin B-Heamatoxylin and reticulin C-PAS and eosin D-Fontana and reticulin