2 Means a new growth Or "neoplasm". In clinical practice, called a tumour.This is not strictly correct, since the term tumour refers to all swellings, e.g. inflammation, haematoma etc., but it is so generally accepted .Oncology (Greek oma = tumour) Is the science of studying neoplasms
3 DefinitionNeoplasm is an abnormal new growth, of cells independent of physiologic growth stimuli (autonomous).Its presence serves no useful purposeIts growth is uncoordinated with that of the surrounding tissueIts growth persists after cessation of the stimuli which provoked its formation
4 In neoplasia proliferation, differentiation and organisation are all disturbed Proliferation: a neoplasm is characterized by partial or complete loss of regulation of mitosis and cell maturationDifferentiation reduction or deletion of the specialized function of the cellsOrganization loss of the morphologic tissue and organ characteristics.
5 Classification of neoplasms According to their clinical behaviour into:Benign tumours, which usually grow slowly and do not interfere with the person's well being or shorten his life, unless the tumour encroaches on a vital organ e.g. the brain or produces harmful substances e.g. excess hormones.Malignant tumours generally are more rapidly growing, destroy and infiltrate the normal structures and unless effectively treated interfere with health and eventually cause death.
6 All tumours, benign and malignant are formed of two basic components:1- Parenchymal neoplastic cells, (proliferating neoplastic cells)2- Supportive stroma of connective tissue and blood vessels and possibly lymphatics
7 Classification of tumours 1. Benign:EpithelialMesenchymalGerm cell tumours2. Malignant:
8 A-Tumours of epithelial origin Classification of TumoursA-Tumours of epithelial origin1-Str. Sq. epithelium Squamous cell papilloma.Squamous cell carcinoma.2-Glandular epithelium AdenomaAdenocarcinoma3-Neuroectoderm NevusMalignant melanoma
9 B-Tumours of Mesenchymal origin Malignant=sarcoma Benign=oma Fibroma ( benign tumor of fibroblasts)Lipoma ( benign tr of lipocytes)Leiomyoma ( benign tr of smooth muscle fibers)Rhabdomyoma( benign tr of striated muscle fibers)Osteoma ( benign tr of osteoblasts)Chondroma ( benign tr of chondrocytes)Angioma ( benign tr of endothelium)
10 C- Tumours derived from more than one germ layer (from totipotential cells) Teratoma (mature)Immature teratoma
11 Characterization of benign and malignant tumours 1- CapsulationBenign tumours grow by expansion leading to pressure atrophy of the surrounding tissue with formation of a fibrous capsule. Though not all benign tumours are encapsulated, but there is always a plane of cleavage around the tumours.
12 Malignant tumours grow by an infiltrative manner that destroys and penetrates the surrounding tissue; they do not develop a capsule. The infiltration tends to occur in anatomic planes of cleavage
13 Comparison between a benign tumor of the myometrium (leiomyoma) and a malignant tumor of similar origin (leiomyosarcoma).
24 Anaplasia:DefinitionIt implies dedifferentiation or loss of structural and functional differentiation of normal cells.eg. Malignant tumours formed of undifferentiated cells are called anaplastic tumours, anaplasia is a marker of cancer.
25 The following cytologic features characterize malignant cells: Nuclear and cellular pleomorphism: wide variation in the shape and size of cells and nuclei.Hyperchromatism: darkly-stained nuclei that frequently contain prominent nucleoli.
27 Nucleo-cytoplasmic ratio: approaches 1:1 instead of 1:4 or 1:6 reflecting enlargement of nuclei. Abundant mitoses: reflect proliferative activity. Mitotic figures may be abnormal (atypical e.g. tripolar, quadripolar or multipolar spindles).Tumour giant cells: containing a single large polypoid nucleus or multiple nuclei.
29 Anaplastic tumours also demonstrate a total loss of tissue architecture e.g. in an anaplastic tumour of uterine cervix, the normal orientation of squamous epithelial cells with respect to each other is lost (loss of polarity).
30 Well-differentiated tumours, whether benign or malignant, tend to retain the functional characteristics of their counterparts such as the production of hormones in tumours of endocrine origin or keratin in squamous epithelial tumours. Anaplastic tumours have no specialized functional activity.