tumor - DEFINITION AND DESCRIPTON
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Tumors can be benign or malignant neoplasms. Benign neoplasms remain localized while malignant neoplasms can spread to other parts of the body through a process called metastasis. The development of tumors is a multi-step process that involves changes to genes that regulate cell growth and behavior, causing cells to proliferate uncontrollably. As tumors progress from benign to malignant, cells acquire further genetic alterations that allow for invasion of surrounding tissues and escape from normal growth controls.
tumor - DEFINITION AND DESCRIPTON
- 1. tumor
- 2. WHAT IS A TUMOUR? a swelling inflammatory – abscess neoplasm - growth
- 3. NEOPLASM • Abnormal growth of cells which persists after initiating stimulus has been removed • Cell growth has escaped from normal regulatory mechanisms • Benign • Malignant
- 4. BENIGN NEOPLASM Cells grow as a compact mass and remain at their site of origin
- 7. MALIGNANT NEOPLASM Growth of cells is uncontrolled Cells can spread into surrounding tissue and spread to distant sites Cancer = a malignant growth
- 10. HOW DO TUMOURS DEVELOP? • There has to be a change to DNA • The change must cause an alteration in cell growth and behaviour • The change must be non-lethal and be passed onto daughter cells
- 11. HOW DO TUMOURS DEVELOP? • Alteration is to more than one gene • Genes concerned are oncogenes/tumour suppressor genes • Sequence of gene alterations from normal to benign to malignant • Intrinsic and extrinsic / inheritance and environment key factors
- 12. CLONALITY Alterations in genes regulating growth and behaviour occur in every cell – monoclonal population Evidence from studying G6PD In heterozygotes cells contain either G6PD A or G6PD B, but tumours in those people consist of cells that all have the same enzyme NORMAL CANCER OR A B A A A A AB B B B B
- 13. HOW DO NEOPLASTIC CELLS DIFFER FROM NORMAL CELLS? Alterations in growth control • proliferation • cell death • factors regulating growth and response Alterations in cellular interactions • cell-cell • cell-stroma
- 14. GROWTH CONTROL • Increased cell proliferation more cells enter cell cycle cell cycle “speeded up” • Cells have changed life span • Alterations in cell death-decreased apoptosis • Modification of cell metabolism • Angiogenesis
- 15. GROWTH CONTROL • Increased or decreased growth factor receptors or altered receptors • Synthesis of growth factors – autocrine or paracrine effect • Excess/modified growth control proteins e.g. oncoproteins
- 16. Increased DNA synthesis and proliferation Growth factor receptor = Growth factor Autocrine Paracrine
- 17. CELLULAR INTERACTIONS Cell-cell interactions Cell-stromal interactions with basement membrane Important for cell and tissue differentiation, embryogenesis, growth regulation
- 18. Ordered Cytoskeleton Cell receptors Basement membrane Desmosomes Disorganised Cytoskeleton Loss of cell receptors
- 19. DIFFERENCES BETWEEN BENIGN AND MALIGNANT NEOPLASMS • Size • Growth characteristics • Vascularity/necrosis • Function • Invasion/metastasis
- 20. BENIGN Nuclear variation in size and shape minimal Diploid Low mitotic count, normal mitosis Retention of specialisation MALIGNANT Nuclear variation in size and shape minimal to marked, often variable Range of ploidy Low to high mitotic count, abnormal mitosis Loss of specialisation DIFFERENCES BETWEEN BENIGN AND MALIGNANT NEOPLASMS
- 21. BENIGN Structural differentiation retained Organised Functional differentiation usually MALIGNANT Structural differentiation shows wide range of changes Not organised Functional differentiation often lost DIFFERENCES BETWEEN BENIGN AND MALIGNANT NEOPLASMS
- 22. DYSPLASIA • Premalignant condition • Increased cell growth • Cellular atypia • Altered differentiation • Can range from mild to severe • Sites -cervix -bladder -stomach
- 23. IN-SITU MALIGNANCY Epithelial neoplasm with features of malignancy • altered cell growth • cytological atypia • altered differentiation BUT-no invasion through basement membrane
- 26. POSSIBLE EVENTS Benign Benign Benign Dysplasia Benign Dysplasia In-situ Benign Dysplasia In-situ Invasive Dysplasia In-situ Invasive In-situ Invasive Invasive Invasive
- 27. TYPES OF NEOPLASMS Benign Malignant Epithelial Connective tissue Lymphoid /haemopoietic Germ cell
- 28. BENIGN EPITHELIAL NEOPLASMS Papilloma • squamous • transitional Adenoma • glandular
- 31. MALIGNANT EPITHELIAL NEOPLASMS Carcinomas Squamous: skin Transitional: bladder Adeno: stomach, colon Basal cell: skin
- 35. CONNECTIVE TISSUE NEOPLASMS Smooth muscle: Leiomyoma Fibrous tissue: Fibroma Bone: Osteoma Cartilage: Chondroma Fat: Lipoma Nerve: Neurofibroma Nerve sheath: Neurilemmoma Glial cells: Glioma
- 37. CONNECTIVE TISSUE NEOPLASMS Smooth muscle: Leiomyosarcoma Bone: Osteosarcoma Fibrous tissue: Fibrosarcoma Cartilage: Chondrosarcoma Fat: Liposarcoma Nerve: Neurofibrosarcoma Nerve sheath: Neurilemmosarcoma Glial cells: Malignant glioma
- 39. LYMPHOID Malignant lymphoma (B and T) Hodgkins Disease BONE MARROW Acute and chronic leukaemia