Lec 1 Introduction to Pathology PDF

Lec -1- Introduction to Pathology *د. مصطفى السعدي* =================================================== The term "pathology" is derived from the pathos of the Greek words which means **disease** and ***logy*** which means **study**. a. ***General pathology***: common changes in all tissues. e.g:...

Lec -1- Introduction to Pathology *د. مصطفى السعدي* =================================================== The term "pathology" is derived from the pathos of the Greek words which means **disease** and ***logy*** which means **study**. a. ***General pathology***: common changes in all tissues. e.g: Inflammation, cancer, aging, edema, hemorrhage b. ***Systemic pathology***: the pathologic mechanisms of various organ systems. e.g. CVS, CNS, GIT...etc. Regarding a disease process, we must be familiar with: 1. ***Etiology*** of a disease means the cause of the disease. If the cause of a disease is known it is called ***primary** etiology*. If the cause of the disease is unknown it is called *idiopathic*. - Genetic. - Acquired (infectious, nutritional, chemical, physical, etc). - Cigarette smoking is a risk factor for lung cancer - Obesity is a risk factor for heart disease. 2. ***Pathogenesis*** means the mechanism through which the cause operates to produce pathological and clinical manifestations. The pathogenetic mechanisms could take place in the latent or incubation period. Pathogenesis leads to morphologic changes. 3. ***Morphologic changes:*** The morphologic changes refer to the structural alterations in cells or tissues that occur following the pathogenetic mechanisms - ***[Gross (macroscopic) changes]***: By naked eye examination. - ***[Histologic (microscopic) changes]***: By light microscope examination. - ***[Ultrastructural changes]**:* By an electron microscope examination. - ***Clinical features***: Signs and symptoms are abnormalities that can indicate a potential medical condition.***[symptom]*** is **subjective**, that is, apparent only to the patient (for example back pain or fatigue). - ***[sign]*** is any **objective** evidence of a disease that can be observed by others (for example a skin rash or lump). 4. ***Diagnosis:*** 5. ***Treatment***: could be: - Medical treatment (tablets, capsules, injection) - Surgical treatment. - Psychological treatment. 6. ***Prevention***: measures to prevent diseases or injuries rather than curing them or treating their symptoms (sanitation, proper nutrition, adequate exercise, vaccinations, and other self-care and public health measures, such as obligatory face masks). 7. ***Prognosis:*** defined as "the determination of the predicted optimal level of improvement in function and the amount of time needed to reach that level. according to prognosis diseases can be classified to: [Subdivisions of clinical pathology] ================================================ 1. **Histopathology**; is concerned with the investigation and diagnosis of disease from the gross and microscopic examination of tissues. 2. **Cytopathology**; is concerned with the investigation and diagnosis of disease from the examination of isolated cells. 3. **Hematopathology**; is concerned with the study of disorders affecting the cells and the coagulation system of blood. 4. **Medical microbiology**; is concerned with the study of infectious diseases and the organisms responsible for them. 5. **Immunopathology; is** concerned with the study of disturbances affecting the immune defense mechanisms of the body, and their contribution to the disease processes. 6. **Chemical pathology**; is concerned with the study and diagnosis of diseases from the chemical changes that occur in tissues and fluids. 7. **Medical genetics**; concerned with the study of abnormal chromosomes and genes and their relevance to disease processes. 8. **Toxicology**; is concerned with the study of the effects of known or suspected poisons on the body. 9. **Forensic medicine (pathology**); concerned with the examination of tissue taken from ***autopsy*** (dead body). **(Autopsy)- (post-mortem examination or morbid anatomy):** It consists of an external and internal examination of the body after death. Morbid anatomy comprises both gross (naked eye) as well as microscopic examinations of the diseased organs and tissues. The post-mortem findings enable the pathologist to reach the ultimate pathological diagnosis, make a clinicopathologic correlation, and finally deduce the cause of death. [Stains used in pathology:] ======================================= 1. **Haematoxylin and eosin stain (H&E):** It is the primary stain used in sectioned slides to reveal their histological details. Haematoxylin has a strong affinity for nuclear chromatin giving blue discoloration, while eosin has a strong affinity for proteins present in the cytoplasm giving pink discoloration. 2. **Periodic acid Schiff stain (PAS):** Special stain used to demonstrate glycogen, neutral mucosubstances, basement membrane, and most types of fungi and parasites. 3. **Stain for microorganisms**: used to demonstrate gram-positive and gram-negative bacteria, acid-fast bacteria, fungi, and parasites. e.g: Gram stain and zeihl Neelsen stain. 4. **Amyloid stain**: e.g. congo red for detection of amyloid. 5. **Perl's stain**: for the detection of iron 6. **Trichrome stain**: used to differentiate between collagen and smooth muscle in tumors, and the increase of collagen in diseases such as cirrhosis. 7. **Prussian blue stain:** This histochemical reaction is sensitive enough to demonstrate minute amounts of iron deposits in blood cells, bone marrow, and spleen. 8. **Immunohistochemical stain(IHC):** is used in histology to detect the presence of a specific protein marker that can assist with accurate tumor classification and diagnosis.