Introduction to Pathology

What is pathology Pathology is the scientific study of disease. In its broadest sense, it is the study of how the organs and tissues of a healthy body change to those of sick person.

The four aspects of a disease process that form the core of pathology ● Etiology ● Pathogenesis ● Pathological change ● Clinical pathological correlation and Prognosis The scope of pathology

Etiology: causes of the disease Pathogenesis: the mechanisms of its development Pathologic changes: the structural alteration induced in the cells and organs of the body. Clinical pathological correlation and Prognosis : the Clinical effects of the pathological changes.

Position (1) Pathology is a bridging between basic science and clinical medicine (2) Pathology is also a practical clinic medicine ( Diagnostic Pathology or Surgical Pathology)

Classification (1) Human pathology The principal aim of human pathology considers structural abnormalities of cells and tissues grossly and microscopically examined from patient ’ s tissues (2) Experimental pathology Experimental pathology researches cellular processes incorporate animal experiment and tissue and cell cultures

1. Human pathology (1) Autopsy (means “ see for yourself ” ) Autopsy is a special operation, performed by specially trained physician, on a dead body

The functions of Autopsy ● Clarify the causes of death ● Diagnosis and treatment quality control ● Recognizing of negligence ● Recognition of new diseases and new diseases patterns ● Source of information ● Provide material for education ● material for scientific research ● Recognition of treatment effectiveness

Biopsy is the removal of a sample of tissue from the body for examination and the tissue will be examined under a microscope to assist in diagnosis (2) Biopsy

(3) Cytology Cytology is responsible for preparation, staining and microscopic examination. (smear, fine needle aspiration)

2. Experimental pathology (1) Animal experiment: Animal experiment is a pathological method using animal model to study diseases within the body.

(2) Tissue and cell culture Tissue and cell culture is that the tissue or cell sample from a human or animal is obtained and maintained in vitro for experimental, diagnostic or therapeutic purposes

Basic examination methods (1) Gross appearance The morphological feature of a lesion (such as size, shape, weight, color, consistency, surface edge, section) is observed by eyes or assisted by using a ruler, steelyard, magnifying glass, or other tools.

Lung cancer

(2) Histologic and cytologic observation The specimens from patients are prepared as a section or smear, then stained and examined by using microcopy

cytologic observationHistologic observation most common: basic formalin fixed → HE (hematoxylin and eosin) stained

（ 3 ） Histochemistry and cytochemistry Histochemistry and cytochemistry is also called special stain method. Some tissue structures and substances (protein, enzyme, nucleic acid, glycogen, lipid) are colored when a chemical group ( carboxyl, phosphoric, or aldehyde) reacts with the stain

PAS (glycogen) → BM Sudan Ⅲ → fat

Immunohistochemistry ● Ag-Ab specific reaction ● Applications Location analysis ( cytokeratin→cell membrane) Clinical diagnosis and distinguishing (diagnosis of tumor histogenesis) (4) others

Leiomyosarcoma Actin (+)

Electron microscope

Filtering membrane TEM (transmitting electron microscope)

Podocyte SEM (scanning electron microscope)

Flow cytometry (FCM)

● One kind of cells→quantitative analysis ● DNA ploidy analysis ● Protein and nucleus acid → quantitative analysis ● Selection of collection of cells application

Nuclei: diameter; circumferen ce; area; volume; morphology Image analysis (IA)

Laser scanning confocal microscope (LSCM) aliving cell observation in situ or development or quantitative

Molecular biology technique ● Polymerase chain reaction (PCR) ● DNA sequencing ● Biochip technique Gene chip (DNA chip) Protein chip (protein microarray) Tissue chip (tissue microarray)

Polymerase chain reaction (PCR)

History of Pathology Autopsy → Organ pathology (1761) LM → Cellular pathology (1854) Ultrastructural pathology with the application of EM (20 century 60s) Immunopathology, Molecular pathology, Genetic pathology, Quantitative pathology

Text of Pathology (1) General pathology: concerned with the basic reaction of cells and tissues to abnormal stimuli that underlie all diseases. (2) Systemic pathology : dedcribe the specific responses of specialized organs and tissues to defined stimuli.