Introduction to Tissue Processing, Molecular, and Clinical Pathology (2024-2025) PDF

INTRODUCTION ,TISSUE PROCESSING , MOLECULAR AND CLINICAL PATHOLOGY ASSOCIATE PROFESSOR DR. ABDULKARIM Y. ALTAIE DEPARTMENT OF PATHOLOGY ALNOOR UNIVERSITY 2024-2025 Pathology pathology is the study (logoy) of suffering (patho). Pathology: is the branch of me...

INTRODUCTION ,TISSUE PROCESSING , MOLECULAR AND CLINICAL PATHOLOGY ASSOCIATE PROFESSOR DR. ABDULKARIM Y. ALTAIE DEPARTMENT OF PATHOLOGY ALNOOR UNIVERSITY 2024-2025 Pathology pathology is the study (logoy) of suffering (patho). Pathology: is the branch of medical science that studies the causes , nature and effects of diseases“ Disease: any abnormality in the structure and /or function of an organ or tissue. Specialties of pathology 1- Histopathology. 2-Hematology 3-Clinical pathology 4-Immunpathology 5-Experimental pathology 6- Molecular pathology  Molecular Pathology ► Definition ► The study of biochemical and biophysical cellular mechanisms as the basic factors in disease. ► Use of nucleic acid based tests to determine diagnosis or prognosis Uses Diagnosis Prognosis Prenatal testing Pharmacotherapy What is clinical pathology? ► Branch of pathology studying changes in chemical composition of the body fluids which help in diagnosis of a disease ► Covers the use of laboratory aids to assess the health, detect a disease state ► Referred to as laboratory medicine because it is a component of the investigative process that leads to the diagnosis and treatment of medical conditions SPECIFIC OBJECTIVES OF CLINICAL PATHOLOGY 1.Disease diagnosis: ► Especially when disease is at sub-clinical stage ► e.g. Examples of tests include tuberculin test for TB and Rose Bengal test for brucellosis 2. Differential Diagnosis: ► e.g., if patient has red urine, it may due to hematuria(intact red blood cells) or hemoglobinuria (lysed RBCs) 3.Determination of the drug effectiveness & toxicity: 4.Prognosis (outcome) of the disease: Biopsy: examination of tissue taken from living body (gross &microscopical examination). Autopsy Also known as a post-mortem examination. Is a procedure that consists of a thorough examination of a dead body to determine the cause and manner of death and to evaluate any disease or injury that may be present. Types of biopsy 1) Incisional biopsy: a portion of tissue from a large lesion is taken-only diagnostic 2) Excisional biopsy: the entire lesion is removed with a margin of adjacent normal tissue-diagnostic & therapeutic. 3) Punch biopsy: by biopsy forceps in the uterus ,cervix, oral cavity & esophagus. 4) Core needle biopsy: by wide bore needle used percutaneously for sampling of internal organs. 5) Curettage biopsy : for diagnosis of internal diseases e.g. curettage of endometrium as diagnostic procedure. Handling of biopsy: Once a biopsy is taken, it should be put in plastic or metal container with adequate amount of fixative ( 10% formalin) which causes rapid denaturation of cellular proteins & prevents autolysis. It should be sent to the lab. with a request form including patient’ s name, age, sex, short clinical notes, type of biopsy, name of tissue submitted , findings of operation & provisional diagnosis. Gross examination General principles for gross examination: 1) Proper identification & orientation of the specimen. 2) Place the specimen on a cutting board & record all the following data ► Type of specimen ► Dimension ( in centimeters) ► Weight ► Shape ► Consistency ► Surgical margins whether included or not involved by the tumor. Histopathological techniques Deals with tissue deals with preparation of tissue for histopathological examination, the aim of these technique is to preserve microscopic anatomy of tissues & to cut tissue in very thin sections( 4-5 microns) this is achieved by passing tissue in a series of process.  Tissue processing can be done manually or mechanically & includes the following processes 1) Fixation. 2) Dehydration. 3) Cleaning. 4) Embedding. 5) Cutting. 6) Staining. 1- Fixation Most fixatives act by denaturating or precipitating cellular proteins which form meshwork that hold other structures & prevent autolysis. The most widely used fixative is 10% formalin. 2- Dehydration Is removal of water molecules from tissues and is achieved by graded alcohol. 3- Cleaning Alcohol replace water in the tissues, removal of alcohol from tissues is by Xylene which creates empty tissue spaces to be infiltrated by wax. 4- Embedding with wax Paraffin wax is used for embedding of tissue which form tissue blocks after cooling. It can be trimmed into thin sections (4-5microns) using the microtom the sections are placed on glass slides and become ready for staining. 5- Staining\Hematoxylin & Eosin (H&E) is the most widely used stain in histopathology Nuclei appear dark blue. Collage & cytoplasm appear pink. Keratin appears pink to red. Special stains 1) PAS ( periodic acid schiff) stain for glycogen & mucin. 2) Congo-red for amyloid. 3) Sudan-black for fat. 4) Gimsa stain for Helicobacter pylori. H. pylori stained dark blue with Gimsa stain Cytology: is the study of normal & abnormal morphologic characteristics of human cells. e.g. fluid cytology , Pap smear from the uterine cervix , FNAC. Thank You