Introduction to Pathology DR:Gehan mohamed

1. Introduction to PathologyDR:Gehan mohamed

2. Pathology • Greek Pathos = suffering; logos = study • Pathology = “The study of suffering.” • Involves: • Study of disease processes and • The structural and functional changes in organs and tissues that cause or are caused by disease.

3. Definition of pathology It is the “Scientific study of disease" . "scientific study of the molecular, cellular, tissue, or organ system response to injurious agents." Pathology serves as a "bridge" or "link" between the preclinical sciences (anatomy, physiology, ……etc.) and the courses in clinical medicine.

4. The Science of PathologyClassification • General pathology: • The study of general reactions of cells and tissues to insults and injuries that are basic to all disease processes. • Systemic pathology: • The study of specific disease processes or reactions as they affect particular organs or organ systems e.g. CVS, CNS, GIT…..etc. • .

5. Applied pathology • Anatomic pathology • Necropsy pathology • Surgical pathology • Cytopathology • Clinical pathology • Forensic pathology

6. Applied pathology • Anatomic pathology: • Making diagnosis by examining tissues. • Necropsy pathology • The study of cadavers to elucidate the cause or causes of death. • Surgical pathology • Examination of tissues excised from living patients in an effort to establish a specific diagnosis. • This is called “biopsy”. • Cytopathology • The study of individual cells primarily as a method to detect malignant (cancer) cells.

7. Applied pathology 2. Clinical pathology • Analysis of various specimens (whole blood, serum, plasma, urine, feces, spinal fluid, sputum, etc.) from patients to facilitate diagnosis, direct therapeutic approach and monitor therapy. 3. Forensic pathology • Subspecialty dealing with medicolegal investigation of death.

8. Methods in Pathology • 1-Biopsy: examination of tissuesfrom the living body to determine the existence or cause of a disease. • Closed biopsy: means the pathologist or clinician put a needle into the mass to obtain a bit of tissue (needle or core biopsy). • Usually won’t give you enough material. • Open biopsy: means an incision was made to obtain a larger mass of tissue. • Excisional biopsy: means the mass or entire organ was removed for diagnosis.

9. Closed or core biopsy

10. Excisional biopsy

11. 2-FNAC = Fine Needle Aspiration Cytology • A thin core needle is used to obtain a few cells from a mass lesion. • Used for: • Superficial mass • Deep mass lesions (with help of CT/USG)

12. FNAC

13. What is the Disease? • It is the “State in which an individual exhibitsan anatomical, physiological(function), or biochemical deviation from the normal”

14. Classification of Diseases: • (A)Developmental – genetic, congenital. • (B)Acquired: (1)Inflammatory – Trauma, infections, immune, etc. (2)Neoplastic – tumors cancers (3)Degenerative – ageing. (4)Metabolic (5)Iatrogenic: Drug induced.

15. What should we Know About A Disease • Definition. • Epidemiology – Where & When. • Etiology – What is the cause? • Pathogenesis - Evolution of dis. • Morphology - Structural Changes • Functional consequences • Management • Prognosis • Prevention Pathology

16. Etiology “Study of the cause of a disease" Knowledge of etiology remains the backbone of: • Disease diagnosis • Understanding the nature of diseases • Treatment of diseases.

17. Etiology “Study of the cause of a disease" Predisposing Causes of Disease: Factors which make an individual more susceptible to a disease (damp weather, poor ventilation, etc.) Exciting Causes of Disease (An etiologic agent): Factors which are directly responsible for a disease (hypoxia, chemical agents , virus, bacteria …. etc.). 

18. Disease Disease Disease Disease Disease Etiology • One etiologic agent several diseases, as smoking. • One etiologic agent - one disease, as Malaria. • Several etiologic agents one disease, as cancer .

19. Pathogenesis The sequence of events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease.

20. CELLS Response to injurious agent Either : • ADAPTING • SUSTAINING REVERSIBLE INJURY • SUFFERING IRREVERSIBLE INJURY AND DYING

21. Clinical Symptoms & Signs • Clinical symptomsare the patient’s complain usually by its own words as pain. • Clinical signs are seen only in the living individual as organomegaly.

22. MORPHOLOGY Morphology remains at the heart of diagnostic pathology. • Morphologic change Characteristic of the disease Diagnostic of the etiologic process • These changes responsible for Functional derangements

23. Morphologic change • The structural alterations caused by a disease maybe classified sequentially: • Gross (macroscopic) changes: appreciated by naked eye (last to be seen, Third) • Histologic (microscopic) changes: appreciated by armed eye (microscope), (Second) • Ultrastructural changes: first to be seen by an electron microscope (First)

24. Changes resulting from a disease go through the following sequence : • Ultrastructural changes • Microscopic changes • Gross changes

25. Morphology (1)Gross appearance: size, shape weight color consistency surface edge, section

26. (2)Microscopic examination for tissue sections fixed in formalin then stained by HE (hematoxylin and eosin) to be examined by light microscope for Histologic and cytologic changes. Hemangioma

27. Histochemistry using PAS stain PAS→BM

28. Immunohistochemistry 1. It is Ag-Ab specific reaction 2. Applications : in diagnosis of tumor histogenesis

29. Immunohistochemistry to diagnose Leiomyosarcoma using actin Actin (+)

30. (3)Ultrastructural observation By using electron microscope) Filtering membrane in the kidney

31. Podocyte SEM (scanning electron microscope)

32. (4)Flow cytometry (FCM) In neoplastic diseases Can determine : 1- If there is One kind of cells→quantitative assesment 2. DNA ploidy analysis (amount of DNA)

33. （5）Image analysis (IA) it can determine Nuclear diameter; circumference; area; volume; morphology

34. （6）Molecular biology technique 1. Polymerase chain reaction (PCR) 2. DNA sequencing

35. Polymerase chain reaction (PCR)

36. prognosis • Expected outcome of the disease, It is the clinician's estimate of the severity,fate and possible result of a disease.  • Good prognosis: suggests recovery is likely. • Poor prognosis: suggests permanent disability or death.