Pathology CAM235Unit 1

Introductionاألمراضعلم

Dr. Moattar Raza Rizvi

Pathology is the study (logos) of suffering (pathos).

It is a discipline انضباط that bridges clinical practice and basic science

Pathology is Scientific study of disease.

More specifically, pathology may be defined as the "scientific study of the molecular, cellular, tissue, or organ system in response to injurious agents or adverse influences."

PATHOLOGY - Definition

Disease is defined as any disturbance of the structure and/or function of the body or any of its constituent parts outside the normal range, especially one that produces specific clinical signs.

Nearly every disease is associated with dysfunction وظيفي at the level of the organ, cell, or اختالل

organelle.

This allows the pathologist الشرعي to identify الطبيبfunctional damage and the cascade تتالي of disease processes on the basis of abnormal structural changes.

DISEASE

• It involves the investigation of the causes (etiology, األمراض أس8باب of disease as well as the underlying السبب (عل8م

mechanisms آلية (pathogenesis) that result in the presenting signs عالمات and symptoms األعراض of the patient

PATHOLOGICAL STUDY OF DISEASE

1. Etiology : This involves the study of pathogens that cause disease األمراض أسباب علم

2. Pathogenesis: the mechanism causing the disease This answers the question of why a certain pathogen causes disease in a certain individual. Sequence of events in the response of cells or tissues to an etiological agent, starting from the initial stimulus to the ultimate expression of disease, without any treatment3. Morphology: the structural features of the disease4. Clinical Significance: the functional features of the disease

CHARACTERISTICS OF DISEASE

• “Study of the cause of a disease"

• An etiologic agent is the factor (bacterium, virus, etc.) responsible for lesions or a disease state.

• Predisposing Causes of Disease: Factors which make an individual more susceptible to a disease (damp weather, poor ventilation, etc.)

• Exciting Causes of Disease: Factors which are directly responsible for a disease (bacteria, viruses, hypoxia, chemical agents, etc.). 

ETIOLOGY

MORPHOLOGICAL CHANGES

Autopsy (necropsy and postmortem examination are synonymous) means to 'see for oneself'.

In other words, rather than relying on clinical signs and symptoms and the results of diagnostic investigations during life, here is an opportunity for direct inspection and analysis of the organs.

Autopsies are useful for: i. determining the cause of deathii. audit of the accuracy of clinical diagnosisiii. education of undergraduates and postgraduatesiv. research into the causes and mechanisms of diseasev. gathering accurate statistics about disease incidence.

AUTOPSIES

المتصورة

الحقائق الهدف

مزمنحاد

تنبؤ نتائج

1. Primary and secondary They may be used to describe the causation of a disease.

Primary means that the disease is without evident cause. Example, primary hypertension is defined as abnormally high BP without apparent cause.

Secondary means that the disease represents a complication of some underlying lesion. Example, secondary hypertension is defined as abnormally high BP as a consequence of some other lesion (e.g. renal artery stenosis).

The words primary and secondary may be used to distinguish between the initial and subsequent stages of a disease, most commonly in cancer.

NOMENCLATURE OF DISEASE

2. Acute and chronic Acute and chronic are terms used to describe the dynamics of a disease.

Acute conditions have a rapid onset, often but not always followed by a rapid resolution.

Chronic conditions may follow an acute initial episode, but often are of deceptive onset, and have a prolonged course lasting months or years.

Subacute, a term not often used now, is intermediate between acute and chronic.

NOMENCLATURE OF DISEASE

3. Benign and malignant Benign and malignant are emotive terms used to classify certain diseases according to their likely outcome. Thus,

Benign tumours remain localised to the tissue of origin and are very rarely lethal unless they compress some vital structure (e.g. brain), whereas malignant tumours invade and spread from their origin and are commonly lethal.

Benign hypertension is relatively mild elevation of blood pressure that develops gradually and causes insidious injury to the organs of the body.

This situation contrasts with malignant hypertension, in which the blood pressure rises rapidly and causes severe symptoms and tissue injury (e.g. headaches, blindness, renal failure, cerebral haemorrhage).

NOMENCLATURE OF DISEASE

4. Eponymous names An eponymous disease or lesion is named after a person who first described the condition. Examples include:

i.Graves' disease: primary thyrotoxicosisii.Paget's disease of the nipple: infiltration of the skin of the nipple by cells from a cancer in the underlying breast tissueiii.Crohn's disease: a chronic inflammatory disease of the gut affecting most commonly the terminal ileum and causing narrowing of the lumeniv.Hodgkin's disease: a neoplasm of lymph nodes characterised by the presence of Reed-Sternberg cellsv.Reed-Sternberg cells: large cells with bilobed nuclei and prominent nucleoli which are virtually diagnostic of Hodgkin's disease.

NOMENCLATURE OF DISEASE

5. Syndromes A syndrome is an aggregate of signs and symptoms or a combination of lesions without which the disease cannot be recognised or diagnosed. Examples :

Cushing's syndrome: hyperactivity of the adrenal cortex resulting in obesity, hirsutism, hypertension, etc.

Nephrotic syndrome: albuminuria, hypoalbuminaemia and oedema; this syndrome can result from a variety of glomerular and other renal disorders.

NOMENCLATURE OF DISEASE

Epidemiology is the study of disease in populations.

It also concerns the identification of the causes and modes of acquisition of disease.

Epidemiology involves the recording and analysis of data about disease in groups of people rather than in the individual person alone.

Knowledge about the occurrence of a disease is important for: a) providing etiological cluesb) planning preventive measuresc) provision of adequate medical facilitiesd) population screening for early diagnosis.

EPIDEMIOLOGY OF DISEASE

Diagnosis is the act of naming a disease in an individual patient.

The diagnosis is important because it enables the patient to benefit from treatment that is known, or is at least likely, to be effective from having observed its effects on other patients with the same disease.

The process of making diagnoses involves: i. taking a clinical history to document symptomsii. examining the patient for clinical signsiii. if necessary, performing investigations

MAKING DIAGNOSES

The ultimate goal of pathology is the identification of the causes of disease, a fundamental objective leading to successful therapy and to disease prevention.

GOALالهدف OF PATHOLOGY

Traditionally, the discipline is divided into general pathology and systemic pathology;

•GENERAL PATHOLOGY: This focuses on the fundamental cellular and tissue responses to pathologic stimuli (e.g. inflammation, tumours, degenerations)

•SYSTEMATIC PATHOLOGY: The descriptions of specific diseases as they affect individual organs or organ systems (e.g. appendicitis, lung cancer, atheroma).

BRANCHES OR PHASES OF PATHOLOGY

GROSS PATHOLOGY (macroscopic pathology, pathological anatomy, morbid anatomy):Refers to the study of disease in which tissues and organs are examined with the unaided eye. 

CELLULAR PATHOLOGY (microscopic pathology, histopathology): Refers to the study of diseased tissues and organs with the aid of a microscope. 

SURGICAL PATHOLOGY: Refers to the study of tissues removed at the time of surgery. 

CLINICAL PATHOLOGY: Refers to the study of disease by examination of blood, urine, feces, skin scrapings, etc. 

IMMUNOPATHOLOGY: Refers to the study of diseases associated with abnormalities of the immune mechanisms of the body. 

SUBDIVISIONS OF PATHOLOGY

1. Gross pathology – macroscopic investigation and observation of disease

2. Light microscopy – thin section of wax or plastic permeated tissues, snap-frozen tissues

3. Histochemistry – microscopy of treated tissue sections (to distinguish cell components)

4. Immunohistochemistry and immunofluorescence – tagged antibodies (monoclonal better)

5. Electron microscopy6. Biochemical techniques – e.g. fluid and electrolyte

balance, serum enzymes7. Cell cultures – also allowing cytogenetic analysis8. Medical microbiology – direct microscopy, culturing

and identification9. Molecular pathology – in situ hybridisation (specific

genes/mRNA), polymerase chain reaction

TECHNIQUES OF PATHOLOGY

What is diagnosis? The formal name(s) used to describe a patients dissease. The process of identifying a disease based on the paitents symptoms, the doctors findings, and the results of investigations and laboratory tests.

Pathognomonic: A sign or symptoms that is specifically distinctive or characteristics of a diseases or pathological condition, so much that it makes the diagnosis (e. d. Koplik’s spots are pathognomonic of measles)

DIGNOSIS

Unit 1 Objectives At the end of this chapter you should be able to answer the following question 1.Define Pathology? 2.What is disease? 3.Write the characteristics of disease? 4.What do you mean by etiology and pathogenesis? 5.Define the 2 main cause of disease? 6.Write the methods for studying the morphological alterations in tissues? 7.How is autopsy useful? 8.Define symptom, onset and prognosis of disease?

Unit 1 Objectives 9.Write the difference between

(a) Primary and secondary disease(b) Acute and Chronic disease(c) Benign and Malignant disease

10.What is Syndrome? Give 2 examples? 11.Define epidemiology and write the importance of epidemiology? 12.Write the process of making diagnosis of disease? 13.Define the 2 branches of Pathology? 14.What are the subdivision of pathology? 15.Name the techniques used to study pathology? 16.What is diagnosis? 17.Write the process of making diagnosis of disease?