Introduction to Pathology By Dr. Gehan Mohamed Dr. Abdelaty Shawky

* Pathology: is the science which studies the nature of the disease. 28/12/1432 * Pathology: is the science which studies the nature of the disease. Every disease occurs due to a structural change in the cell, tissues and organ of the body so it doesn’t function normally.

Pathology Classification 28/12/1432 Pathology Classification 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.

28/12/1432 Applied pathology 1. Anatomic pathology: a. Necropsy pathology b. Surgical pathology c. Cytopathology 2. Clinical pathology. 3. Forensic pathology. Necropsy pathology: trying to find out the cause of death. Surgical pathology: trying to find out the type of disease process going on in a living person. Cytopathology: we study individual cells from the body and try to find out the different disease processes by studying the cells.

Anatomic Pathology: Necropsy pathology: Surgical pathology: 28/12/1432 Anatomic Pathology: Making diagnosis by examining tissues. Necropsy pathology: Examination of tissues excised from cadavers in an effort to establish the cause of death. This is called “autopsy”. Surgical pathology: Examination of tissues excised from living patients in an effort to establish a specific diagnosis. This is called “biopsy”. Cytopathology: The microscpocic study of exfoliated cells within body fluids. PAP smear: we study the exfoliated cells (cells being shed off the cervix naturally) from the cervix. This is an example of cytopathology. FNAC = fine needle aspiration cytology.

2. Clinical pathology: 3. Forensic pathology: 28/12/1432 2. Clinical pathology: Analysis of various specimens (whole blood, serum, plasma, urine, stool, CSF, sputum, etc.) from patients to facilitate diagnosis, direct therapeutic approach and monitor therapy. 3. Forensic pathology: Subspecialty dealing with medicolegal investigation of death. Clinical pathology: we obtain different fluids from the body (such as semen or urine to look for kidney disorders).

28/12/1432 Biopsy - Examination of tissues from the living body to determine the cause of a disease. a. Closed biopsy (needle or core biopsy): The pathologist or clinician put a needle into the mass to obtain a bit of tissue. Usually won’t give you enough material. b. Open biopsy (incisional biopsy): - An incision was made to obtain a larger mass of tissue. c. Excisional biopsy: - Excision of the whole mass for diagnosis.

Needle or core biopsy 28/12/1432 Upper left image: thick bore needle. Middle image: thick bore needle is inserted. Lower right image: pieces of tissue is obtained. Depending on the bore of the needle, you can obtain varying thickness of tissues from the patient.

28/12/1432 Excisional biopsy You see a black lesion on the skin. This is malignant melanoma. In this image, the clinician excised the entire thing and sent it to the pathologist. This is “excisional biopsy”.

FNAC = Fine Needle Aspiration Cytology 28/12/1432 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)

28/12/1432 FNAC

The Disease: The structural and functional changes in organs and tissues due to exposure to an irritant (causative agent of the disease).

* Classification of Diseases: A. Developmental: genetic, congenital. B. Acquired: 1. Inflammatory . 2. Neoplastic e.g. Tumors 3. Degenerative e.g. Ageing. 4. Metabolic .

What should we know about the disease? Definition. Epidemiology: Where & When. Etiology: What is the cause? Pathogenesis: Evolution of dis. Morphology: Structural Changes Complications. Management Prognosis Prevention

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

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 or simply the mechanism of disease occurrence. 35

MORPHOLOGY OF THE DISEASE Gross (macroscopic) changes: By naked eye examination. Histologic (microscopic) changes: By light microscope examination. Ultrastructural changes: By an electron microscope examination. 37

(1). Gross appearance: Size. Shape. Weight. Color. Consistency. Surface. Edge, section.

(2). Microscopic examination: for tissue sections fixed in formalin then stained by H&E (hematoxylin and eosin) to be examined by light microscope. Fatty liver Normal liver Fatty liver Hemangioma

Prognosis Expected outcome (fate) of the disease. Good prognosis: suggests recovery is likely. Poor prognosis: suggests permanent disability or death.

Welcome to Pathology