Explore comprehensive answers in Oncopathology & Histopathology for General Pathology. Master cancer diagnosis, tissue analysis, and key concepts essential for
1. Differentiate between benign and malignant tumours. Benign tumours: - Well differentiated - Encapsulated and well circumscribed - Do not invade locally or metastasize - Remain at primary site - Slow growth rate - Amenable to surgical removal Malignant tumours: - Most are anaplastic; variable differentiation - Non-encapsulated - Locally invasive, cause tissue damage - Ability to metastasize from primary site - Rapid growth rate - Surgical intervention less effective 2. Define differentiation, anaplasia, pleomorphism, and dysplasia. - Differentiation: How similar tumour parenchymal cells are to normal parenchymal cells in morphology and function - Anaplasia: Lack of cellular differentiation - Pleomorphism: Differences in cell appearance (shape, size, features) - Dysplasia: Disorderly cellular growth 3. Give two examples each of: a) Carcinomas: - Adenocarcinomas - Squamous cell carcinomas b) Sarcomas: - Fibrosarcomas - Osteosarcomas 4. Define choristoma and hamartoma. - Choristoma: Group of cells found in locations where they are not normally found (ectopic cells) - Hamartoma: Group of cells clumped together in an unusual way 5. List the hallmarks of cancer. - Self-sufficiency in growth signals - Insensitivity to growth inhibitory signals - Limitless replicative potential - Evasion of apoptosis - Altered cellular metabolism - Sustained angiogenesis - Ability to invade and metastasize - Evasion of the immune system - Genomic instability - Tumour-enabling inflammation 6. Name five oncogenic viruses and the cancers they cause. - Epstein-Barr Virus (EBV) - Burkitt Lymphoma, Nasopharyngeal carcinoma - Human T-cell Leukemia Virus (HTLV) - Adult T-cell Leukemia - Hepatitis B Virus - Hepatocellular carcinoma - Human Papilloma Virus (HPV) - Cervical cell carcinoma, Anal carcinoma - Human Herpes Virus 8/Kaposi Sarcoma-associated Herpes Virus - Kaposi Sarcoma 7. Define tumour markers. Substances whose presence indicates the presence of a neoplasm in the body. They can be enzymes produced in elevated amounts, proteins only produced in embryogenesis, or ectopic hormones from tumours. 8. Give examples of tumour markers and the conditions they indicate. - Alpha-fetoprotein (AFP) - Liver, yolk sac tumours - Carcinoembryonic Antigen (CEA) - Various carcinomas - CA-125 - Ovarian cancer - CA 19-9 - Pancreatic cancer - CA 15-3 - Breast cancer 9. State the uses of tumour markers. - Diagnosis of malignancy - Prognosis of malignancy - Detection of minimal residual disease - Determination of therapy - Investigation of drug resistance 10. Define cytopathology. The study of the effect of diseases on individual cells morphologically. Includes the changes cells go through as a result of disease. 11. Define histopathology. A branch of pathology that deals with the study of the effects of diseases on individual tissues. 12. What is a laboratory request form? An official form of communication between a clinician and laboratory staff. Contains details on the procedures requested by the clinician for the laboratory staff to perform. 13. Define tissue fixation. A histological method of preservation of tissue specimens that includes physical and chemical methods that stop vital cellular processes while maintaining tissue shape and volume for further histologic/cytologic examination. 14. Define tissue decalcification. The process of removal of minerals from calcified tissues to allow preparation of thin tissue sections for examinations. 15. Define fine needle aspiration (FNA). A method of sample collection in which a superfine needle is used to collect cells from the body. These cells are aspirated and placed on a slide for examination. 16. Define aspiration cytology. A minimally invasive procedure in which study of cells is obtained by invading body organs minimally and collecting specific cells which are taken out and further examined. 17. Define exfoliative cytology. Study of cells obtained from skin and mucous membranes. Could be obtained by brushing or washing of membranes. 18. Define immunohistochemistry. The use of specific antibodies to identify and illustrate antigens. An immunologic reaction whereby antibodies specific to certain antigens are used to show their presence in tissues. 19. What are frozen sections? Tissue samples prepared using a cryostat to cut and freeze them for the purpose of rapid diagnosis. Can be done during an operation. 20. List the components of a laboratory request form. Patient's information: - Full name of patient, age, gender, requesting clinician's name Specimen information: - Type of procedure requested (e.g., biopsy) - Location of specimen (e.g., laparoscopy left breast) Clinical information: - Should be clearly written by clinician - Should include previous reports on any procedure performed on the patient - Drawings can be used for further illustration Laboratory test required: - Can be ticked from various choices or written down Laboratory information: - Filled by laboratory staff - Contains time and date when specimen was received - Rejection criteria if conditions not met (e.g., insufficient specimen) 21. Define fixatives and give examples. Fixatives are chemicals used in histology to preserve tissue specimens. They work by arresting vital cellular processes while maintaining shape and volume of cells for further histologic/cytologic examination. Examples: - Chemical fixatives: Formalin (10%), aldehydes (formaldehyde, glutaraldehyde), oxidizing agents (potassium dichromate, potassium permanganate), protein denaturing agents (methyl alcohol, ethyl alcohol, acetic acid) - Physical fixatives: Heat, microwave 22. State the functions of tissue fixation. - Prevent autolysis and bacterial infections - Maintain shape and volume of cells for further processes such as staining - Keep cells as close to their living state as possible 23. Give examples of chemical fixatives. - Aldehydes - Formaldehyde, glutaraldehyde (make covalent bonds between proteins to maintain cell structure) - Oxidizing agents - Potassium dichromate, potassium permanganate (mostly used as secondary fixatives) - Protein denaturing agents - Methyl alcohol, ethyl alcohol, acetic acid (denature cellular proteins) - Miscellaneous fixatives: Mercury chloride (unsafe as it causes kidney damage) 24. Give examples of physical fixatives. - Heat - Microwave - Allows use of controlled heat; low heat leads to poor staining, high heat leads to vacuolization and overstaining of cytoplasm; rapid, non-chemical technique 25. Define decalcification and state tissues that require it. Decalcification is the process of removing minerals from calcified tissues to enable preparation of thin sections for examinations. It enables a microtome to cut through tissue such as bone. Tissues requiring decalcification: - Bone - Teeth - Calcified organs - Some tumors such as fibroids - Bone margins of amputated organs - Bone marrow specimens 26. List chemical agents used for decalcification. - 10% Nitric acid - Formal nitric acid - Formic acid - Potassium formate and formic acid - Chelating agents such as EDTA 27. Differentiate between aspiration cytology and exfoliative cytology. Aspiration cytology: - Involves study of cells obtained by invading body organs using an instrument - Examination of removed aspirates - Example: Fine needle aspiration Exfoliative cytology: - Involves study of cells obtained from body surface and membranes such as skin - No need to invade body organs - Examples: Urine cells, bronchial washing, bronchial brushing 28. Give three examples of exfoliative cytology techniques. - Pap smear of the cervix - Urine cytology - Bronchial washing/brushing 29. What is a Pap smear used for? Detection of squamous cell carcinoma of the cervix. 30. Outline the steps in routine tissue processing (paraffin technique). - Fixation - Using 10% formalin to maintain shape and volume - Dehydration - Using increasing concentrations of alcohol to remove water from tissue - Clearing - Using xylene to remove alcohol