BIOL131 Lec 4 - Diagnosis of Disease PDF

BIOL131 red stuff = bad stuff Diagnosis of disease Dr. Cheryl Hawkes B76 Furness [email protected] Hospital lab diagnoses Pathology is the scientific study of causes and effects of disease Encompasses: • Histology and cytology • Microbiology • Haematology • Clinical chemistry • Clinical...

BIOL131 red stuff = bad stuff Diagnosis of disease Dr. Cheryl Hawkes B76 Furness [email protected] Hospital lab diagnoses Pathology is the scientific study of causes and effects of disease Encompasses: • Histology and cytology • Microbiology • Haematology • Clinical chemistry • Clinical genetics Route to diagnosis • Different diseases elicit different effects • Manifestation is often at diagnosis e.g. diabetes mellitus Glucose levels • Identifying underlying disease process • Allows treatment of cause not just symptoms • Lead to better patient care Methods for making a diagnosis Tissue type: • Blood - cell abnormality, biochemical markers • Urine/faeces – clinical chemistry, cytology • Biopsy/resection - direct histological examination Technologies: • Imaging: computerised tomography, magnetic resonance imaging, ultrasound scans, etc. • Biomarker detection and DNA (genetic) based technologies - small number established, more in development/clinical trials, often in combination Imaging methods – whole organs • An ultrasound scan, sometimes called a sonogram, is a procedure that uses high frequency sound waves, low resolution Brain tumour CT MRI • Computerised tomography (CT) scan uses X-rays to image organs quickly, less detail ultrasound • Magnetic resonance imaging (MRI) uses strong magnetic fields and radio waves to image organs in more detail, slower than CT Imaging methods can indicate tumour abnormalities but diagnosis cannot be based on imaging alone Marreiros and Miguel 2016 Medicine DOI:10.3384/diss.diva-130791 Imaging methods – from organs to cells Histology: the study of the structure of animal and plant tissues as visualised Human brain slice Cytology: study of the microscopic appearance of cells under the microscope Cortical pyramidal neurons x40 Histological features • Cells appear different in every tissue / organ • Size/shape, cellular content, rate of division, organisation colon testis skin • Need to know normal histological appearance to determine histopathological / cytological changes characteristic of disease • Potentially life-or-death decision What is cancer? • A group of diseases in which abnormal cells divide and grow unchecked • Abnormal cells invade surrounding tissues = invasion/malignancy • Spreading of cancer from its original site to other parts of the body = metastasis • Changes (mutations) in DNA may lead to permanent alteration of normal cellular growth • Proliferate (divide) in a poorly-regulated manner → lump/tissue mass = neoplasm (new growth) Moodle link: Molecular cell biology. Lodish et al. 8th Ed. Pg 1135 - 1143 Cancer cells do not respond to regulatory signals • Normal cells respond to external signals and regulatory systems & undergo death if stress cannot be overcome • Neoplastic cells do not respond to regulator signals i.e. they are ‘transformed’ • A neoplastic mass of cells is known as a tumour, but a tumour is not necessarily ‘cancer’ cancer Cell differentiation Differentiation = immature cells becomes mature cells with specific function Neoplastic transformation • Loss of differentiation – cells become more like precursor cells • Well differentiated = cancer cells look similar to normal tissue cells (i.e. still differentiated) • Poorly differentiated (anaplasia) = cancer cells very dissimilar to normal tissue • Less differentiated = more aggressive progression • Loss of anchorage-dependant growth • Loss of contact inhibition Campbell and Reece 10th Ed. pg 299-301 Campbell and Reece 11th Ed. Pg 297 -299 Features of loss of differentiation Atypical cytology of neoplastic cells 1. Variation in shape and size (pleomorphism) of: 1. Cells – cellular pleomorphism 2. Nuclei – nuclear pleomorphism 2. Increase in nuclear staining = nuclear hyperchromatism 3. Increase in size of nucleus relative to cytoplasm Normal epithelium Neoplastic epithelium State of differentiation correlates with tumour behaviour. Less differentiated = more aggressive Hudish et al. 2011 Cancer Prevention Research 5(2):283-9 Pancreatic cancer Cancerous cells Normal cells https://theconversation.c om/pancreatic-cancer-isreally-four-separatecancers-study-55294 https://creativecommons. org/licenses/by-sa/4.0/ Benign vs Malignant • If the margins are well defined and the tumour remains localised = benign Adenoma (benign tumour in glandular structure) • Does not create problems unless it impinges on the tissue • If the margins are poorly defined and the neoplastic cells invade surrounding tissues = malignant & cancerous • 80% of cancers come from epithelial origin i) glandular tissue (e.g. breast, prostate) ii) squamous cell = linings (e.g. gut, cervix) Invasive Carcinoma Adjusted from Figure 24.8 Lodish et al. 7th ed. © W.H. Freeman and Co. Metastasis Invasion of tissue away from original tumour growth via blood/lymph = metastasis Tumours >2 mm diameter = hypoxic environment, so tumour produces its own blood supply to promote further growth Tumours released into blood or lymph via passive process, exit the vessels in particular tissues • will still have the pathology of the original cell Primary tumour eg breast enter blood / angiogenesis lymphatic vessels Transport exit vessels establishment / proliferation Metastasis eg lung Summary of cancer-related terms Term Definition Dysplasia Abnormal growth or development Anaplasia Reversion of cell to primitive/undifferentiated state Neoplasia Formation of tumour Tumour Abnormal, unregulated new growth of tissue Benign Not threatening to health or life Malignant Invasion of surrounding tissue/Tendency to metastasize Metastasis Spread of cancer from site of origin Diagnosis of cancer Oncology is the study and treatment of cancer Histological examination of the suspect tissue/cells, examine cellular characteristics and distribution of neoplastic cells Imaging methods can indicate tumour abnormality, location, changes over time but diagnosis cannot be based on imaging alone Biomarker detection / PCR based technologies are in development Precision diagnosis leads to tailored therapy for tumour type Diagnosis of neoplasia - tissues Techniques to obtain tissue samples: • Needle biopsy - cutting needle • tissue sample 1-2 mm wide x 2 cm long • All tissues can be sampled even brain lesions • Endoscopic biopsy – small forceps • Tissue sample 2-3mm • GI, respiratory, genital and urinary tracts • Incisional biopsy – scalpel • Portion of surgically accessible lesion removed • Excisional biopsy • Whole lesion surgically removed • Resection • A large tissue sample …Then process for histological analysis Diagnosis of neoplasia - cells Techniques to obtain cell samples: • Shed naturally into body fluid • e.g. urine, sputum • Aspiration by needle • e.g. Blood, bone marrow, fine needle aspiration of solid tumours (e.g. breast, thyroid) • Exfoliation – scraping or brushing • e.g. gastrointestinal tract or cervix • spatula rotated to ensure complete sampling of start of cervical canal Screening for cervical cancer using cytology Female reproductive system • Majority of work for the NHS cytology labs is focused around the cervical screening program • Accounts for 2% of cancers among females. • In the UK, first screening invite at age 25 • ‘Smears’ should be repeated every 3 or 5 years depending on age • Fundamentals of Biomedical Science. Cytopathology: Chapters 3 & 4 Cervical screening - overview https://www.youtube.com/watch?v=MOeHraG1FkQ The cervix Layers of squamous epithelial cells (ectocervix) Squamocolumnar junction (transformation zone) (endocervix) https://histologyblog.com/2013/01/20/histoquarterly-cervix/ https://www.proteinatlas.org/learn/dictionary/normal/cervix,+uterine/detail+2 Cervical stroma influenced by ovarian hormones e.g. Oestrogens Columnar epithelium near the squamocolumnar junction exposed to a hostile environment Induced growth of stratified squamous epithelium (squamous metaplasia) in the “transformation zone” Human papillomavirus (HPV) • 80% prevalence; 99% of cervical cancer associated with HPV • Skin or Sexual transmission • > 130 types, associated with varied diseases • HPV-16 & 18 thought to contribute to 70% cervical cancers • HPV infection: Notable HPV types and associated diseases • increased proliferation of epithelial cells • often cleared by immune system • viral genome integrated into cellular DNA Campbell and Reece 10th Ed pg1126 / 11th Ed pg 1120 & 924 Screening for cervical cancer cells • Scrape cells from ectocervix and lower cervical canal with spatula or brush • Smear onto glass slide, fix and stain - cervical smear (or pap test) = exfoliative cytology • Looking for Cervical intraepithelial neoplasia (CIN) • Colposcopy (with Biopsy) required to examine deeper tissue https://www.eurocytology.eu/en/course/933 Cervical intraepithelial neoplasia (CIN) • Severe cell abnormality (atypia) and dysplasia (growth) • Three grades – dependant on proportion of epithelial thickness containing neoplastic cells • Restricted to epithelium (localised) https://www.cancerquest.org/patients/cancer-type/cervical-cancer Remember – neoplastic cells does not necessarily = malignant cancer • Cells may progress slowly between grades • Screening costs NHS ~ £157 million NHS screening programme for cervical cancer Previous method based on cervical cytology Look for abnormal cells - cell abnormalities Test HPV DNA From 2020 Piloting Test HPV DNA - positive for HPV (16 & 18) Test HPV with samples collected at home Cytology – look for abnormal cells Colposcopy Colposcopy Invite for cytology screen HPV vaccination associated with decreased risk of cervical cancer Drolet et al. 2019 Lancet 394(10197):497-509