Lecture 1.pdf

Auto stimulation e  Neoplasia: an abnormal mass of tissue the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after the cessation of the stimuli which evoked the change.  Fundam...

Auto stimulation e  Neoplasia: an abnormal mass of tissue the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after the cessation of the stimuli which evoked the change.  Fundamental to the origin of all neoplasms are heritable (genetic) changes that allow excessive and unregulated proliferation that is independent of physiologic growth-regulatory stimuli.  made up of transformed or neoplastic cells which is largely determines the biologic The parenchyma behavior of the tumor, and from Components of which the tumor derives its name. both benign and malignant tumors which is supporting, host- derived, non-neoplastic, made up of connective tissue, blood The Stroma vessels, and host-derived inflammatory cells therefore it is crucial to tumor growth.  Comparison between Benign and Malignant tumors Benign tumor Malignant tumor (1) Usually surrounded by fibrous Have no capsule capsule. (2) Slow growing Grow fast (3) Grow locally, project over the affected surface. Grow by invasion Metastasize to distant areas (4) No metastasis from the site of origin (5)Well differentiated parenchymal Range from well to moderate to cells undifferentiated(anaplastic) (6) Amenable to local surgical Return after surgical removal and need removal for chemo or radiotherapy  NOMENCLATURE Benign Tumors  benign tumors are designated by attaching the suffix -oma to the cell type from which the tumor arises, a benign tumor arising in fibrous tissue is a fibroma; a benign cartilaginous tumor is a chondroma.  The nomenclature of benign epithelial tumors is more complex: classified according to their macroscopic , microscopic pattern or by their cell origin.  Examples of benign epithelial tumors actide gland (1 = = applied for the tumors of glandular origin Adenoma or those that exhibit glandular pattern like renal tubular adenoma. are benign epithelial neoplasms, growing on any Papillomas surface, that produce microscopic or macroscopic &finger-like fronds. s is a & mass that projects above a mucosal surface, as Polyp in the gut, to form a macroscopically visible structure. muss 54% are hollow cystic masses; typically they Cystadenomas are seen in the ovary. 5. 9955IG 83 a cine % "gey gland concer salivary > &5-5 S ,% Cartilage Bone ↳ is mmxtumors  WSome of the tumor cells may undergo divergent differentiation, creating so-called - mixed tumors. The best : example is mixed tumor of salivary gland. These tumors have obvious epithelial components dispersed throughout a fibromyxoid stroma, sometimes harboring islands of- cartilage -- or bone, and the preferred designation of these neoplasms is pleomorphic adenoma. -5 0414 = Adenoma Papilloma Br bist rosis + Bloels ↑ Wi singer like Structure  Malignant tumors  Malignant neoplasms arising in mesenchymal tissue or its derivatives are called sarcomas, ex: fibrosarcoma and chondrosarcoma.  Malignant neoplasms of epithelial cell origin are called carcinomas. Carcinomas that grow in a glandular pattern are called adenocarcinomas, and those that produce squamous cells are called squamous cell carcinomas and cholangiocarcinoma for those originate in the bile.  Exceptions  Teratomas: originate from totipotential stem cells such as those normally present in the ovary and testis , Such cells have the capacity to differentiate into any of the cell types found in the adult body , so it may contain bits of bone, epithelium, muscle, fat, nerve, and other tissues.  Lymphoma: malignant tumor of the lymphoid tissues.  Mesothelioma: tumor of the serous membranes.  Melanoma: benign tumor of the melanocytes while malignant melanoma refer to malignant tumor of melanocytes  Special terms  Hamartoma: is a malformation that presents as a mass of disorganized tissue indigenous to the particular site. ex: hamartomatous nodule in the lung containing islands of cartilage, bronchi, and blood vessels.  Choristoma: This congenital anomaly is better described as a heterotopic rest of cells. For example, a small nodule of well-developed and normally organized pancreatic tissue may be found in the submucosa of the stomach, duodenum, or small intestine.  CHARACTERISTICS OF BENIGN AND MALIGNANT NEOPLASMS There are four fundamental features by which benign and malignant tumors can be distinguished. Differentiation and anaplasia Rate of growth Local invasion Metastasis.  Perchym - Highly differtion a & > - 1-Differentiation and Anaplasia -  Refer only to the parenchymal cells that constitute the transformed elements of neoplasms.  The differentiation of parenchymal cells refers to the extent to which they resemble their normal forebears morphologically and functionally. -84 -  Ex. In benign tumor.. lipoma is made up of mature fat - cells laden with cytoplasmic lipid vacuoles. Tuner - & Lipoma Gross and microscopic  Malignant neoplasms are characterized by a wide range of parenchymal cell differentiation, from surprisingly well differentiated to completely undifferentiated. Ex. Well- differentiated squamous cell carcinomas elaborate keratin.  Malignant neoplasms that are composed of undifferentiated cells are said to be anaplastic.  Anaplasia occur either because some tumors originate from the stem cells of the normal tissues or because the dedifferentiation occur during the carcinogenesis.  Anaplastic cells display marked pleomorphism (i.e., marked variation in size and shape).  Nuclei are extremely hyperchromatic and large the nuclear- to-cytoplasmic ratio may approach 1 : 1 instead of the normal 1 : 4 or 1 : 6.  The chromatin is coarse and clumped.  Nucleoli may be of astounding size.  More important, mitoses are often numerous and distinctly atypical; anarchic multiple spindles may be seen and sometimes appear as tripolar or quadripolar forms. Squamous cell carcinoma Rhabdomyosarcoma Tripolar Mitosis  Metaplase > - first step step Third-camera soun W Dysplasia is encountered principally in the epithelia. It is a - loss in the uniformity of individual cells and in their architectural orientation. Dysplastic cells exhibit considerable pleomorphism and often possess hyperchromatic nuclei that are abnormally large for the size of the cell. Mitotic figures are more abundant than usual, with removal of the putative inciting causes, the epithelium may revert to normal. Dysplasia  2-Rate of Growth Some benign tumors grow very fast like leiomyoma of uterus influenced by circulating level of estrogen and then regress and being fibro- calcific after menopause. The rate of growth of malignant tumors correlates in general with their level of differentiation. In other words, rapidly growing tumors tend to be poorly differentiated.  Rate of Growth Sire progras = dis% Tumer 4 I There is wide variation in the rate of growth. Some grow slowly - for years, then enter a phase of rapid growth, signifying the - - - emergence of an aggressive subclone of transformed cells. Others grow relatively slowly and steadily, and there are exceptional instances when growth comes almost to a standstill. in 9 911sne , Rapidly growing malignant tumors often contain central areas of ischemic necrosis because the tumor blood supply fails to provide oxygen for the expanding mass of cells.  Cancer Stem Cells and Lineages There is a hypothesis that tumors have a stem cells analogy to those of the normal tissues to provide and sustain the tumor growth.  3- Local invasion  A benign neoplasm remains localized at its site of origin. Most of benign tumors are encapsulated like fibroma but others are not encapsulated like uterine leiomyoma.  Cancers grow by progressive infiltration, invasion, destruction, and penetration of the surrounding tissue, some of slowly growing malignant tumors show capsule but microscopic inspection reveal crab like invasions. In hematogenous spread arteries are penetrated less readily than are veins. the liver and lungs are the most frequently involved secondary sites in hematogenous dissemination.  EPIDEMIOLOGY Incidence of cancer depend on several factors: (1) Environmental causes: indicated by presence of certain cancer in certain area in higher ratio than other areas. (2) Age: frequency of cancer increases with age. The rising incidence with age may be explained by the accumulation of somatic mutations associated with the emergence of malignant neoplasms, the decline in immune competence that accompanies aging also may be a factor.  ad / EPIDEMIOLOGY (3) Heredity: Hereditary forms of cancer can be divided into three categories :- - A) Inherited Cancer Syndromes: Inherited cancer syndromes include several well-defined cancers in which inheritance of a single mutant gene greatly increases the risk of developing a tumor. ef > - Tamerin ey2  Childhood retinoblastoma is the most striking example of this - category. The child how have this mutation have- 10000 fold risk to develop retinoblastoma , an other example is adenomatous - polyposis syndrome. B. Familial Cancers: Virtually all the common types of cancers that occur sporadically have been reported to occur in familial forms. Examples include carcinomas of colon, breast, ovary, and brain. C. Autosomal Recessive Syndromes of Defective DNA Repair: this characterized by chromosomal or DNA instability. One of the best examples is xeroderma pigmentosum , in which DNA repair is defective.