Neoplasia I study notes General - tumors are new, useless organs - cancers (malignant neoplasms) invade and spread to remote sites (metastasize); benign tumors cannot invade or spread to remote sites, but they can cause problems by compressing local structures - benign tumors are usually round like balls; cancers look like cauliflowers, ulcers, or else simply expand the organ - one out of every five people who die this year will die of tumors - a tumor/neoplasm may be thought of as an attempt by the body under some stimulus to make some new sort of organ - tumors are like organs - all have parenchyma and stroma, cells usually look similar to cells in the organ where tumor arose, and cells will continue to perform some of the functions of the parent organ - tumors are different from organs - they don't contribute to homeostasis, usually grow more rapidly, some benign and all malignant tumors never cease togrow, most tumors show some derrangement of histologic architecture, and malignant tumors are locally invasive and have metastatic potential - tumor is either benign or malignant - benign - cells resemble normal cells, usually are spherical and compress the surrounding tissues, grow slowly with few mitotic figures, and never metastasize - malignant - generally grow more rapidly, cells differ morphologically and functionally from normal cells, and tumor architecture is less organized than that of parent tissue, tumor cells are locally invasive - the tumor grows into the surrounding tissue and destroys it, and the tumor will eventually metastasize spreading to another site remote from the original tumor - malignant tumor and cancer are synonymous - each cell has a cell of origin - tumor cells almost always mimic one cell type of some normal organ - cells may continue to elaborate keratin, hormones, etc. - squamous cell carcinomas - arise anywhere there is a statified squamous epithelium, either healthy or metaplastic - keratin will stain orange-red on H&E - pearls - desmosomes - tonofilaments - adenocarcinomas - these arise anywhere there are glands, even single-celled glands - lumens - glands-within-glands - mucin - other secretory products, depending on gland of origin - cells forming cohesive nests, or at least sticking to one another - signet-ring cells containing mucin, alone or in clusters - adenomas exhibit most of the same features, and look benign - spindle-cell sarcomas - these arise anywhere there is connective tissue - look for cells with elongated nuclei running parallel, with at least a modest amount of cytoplasm - leukemias and lymphomas - look for cells that resemble blood precursors, not sticking tightly together - benign tumors may cause problems - the tumor may secrete something in excess - tumor may compress surrounding structures - a few benign tumors sometimes transform into malignant tumors - malignant tumors in U.S. - males - prostate, lung, colon - female - breast, lung, colon - lung is most fatal cancer - cancer is the leading cause of death in the U.S.of females - appearance of cancers - gross appearance is one of three patterns 1) exophytic - tumor grows as a lump, often with a cauliflower-like surface - malignant tumors seldom appear encapsulated 2) endophytic - tumor grows as an ulcer 3) infiltrating - tumor cells invade an organ diffusely without changing its shape - any cancer is likely to exhibit hemorrhage and/or necrosis, grossly and microscopically; these results from the cancer cells invading the tumor's own blood vessels - microscopic - well-differentiated to poorly differentiated - malignant- looking cells - increased nuclear DNA, increased nuclear/cytoplasmic ratio, hyperchromatic nucleus, caorsening of chromatin, wrinkled nuclear edges, multinucleation, macronuclei - numerous and bizarre mitotic figures - failure to mature along normal functional lines - cells of widely varying sizes - loss of orientation of cells to one another - there may also be microscopic visible invasion and/or indirect evidence (hemorrhage and necrosis; either is important evidence that the tumor in question is malignant) - how malignat tumors invade - local infiltration - invasion of surrounding tissues; for some reason, tendon, cartilage, and elastic tissue almost never get invaded - metastatic spread - four routes 1) seeding of serosal surfaces 2) mechanical transplantation 3) via lymphatics - tumors spread first to regional lymph nodes, then to any lymph nodes or organs 4) via blood vessels - regardless of the route of spread certain tumors have unexplained preference for certain metastatic sites - requirements for successful metastatic spread - basement membrane and endothelial penetration, attachment to metastatic site, stromal induction - grade and stage of metastatic spread - tumor grade I - well differentiated, cells look like normal organ II - not so well-differentiated III- worse IV- even worse V - worst of all - tumor stage stage I - might mean the tumor is smaller than 1 cm diameter, without metastases stage II - might mean the tumor is larger than 1 cm and/or is symptomatic and/or there are metastases to the regional lymph nodes stage III - might mean the tumor has infiltrated a non-resectable structure and/or there are distant metastases - alternate system - T for tumor - T1 - might mean primary tumor less than 1 cm in diameter - T2 - might mean primary tumor is larger than 1 cm in diameter - T3 - might mean primary tumor is invading something non-resectable - N for regional lymph nodes - N0 - would mean no tumor in regional lymph nodes - N1 - might mean tumor in a few nearby lymph nodes - N2 - might mean many nodes, or some nodes farther downstream involved - M for metastases - M0 would mean no metastases - M1 would imply distant metastases - generally tumors of high gradepresent at high stage, while tumors of low grade present at low stage - a hamartoma is not a tumor, but is a developmental anomaly which contains the same tissues as the organ in which it is found, but in the wrong proportions - a choristoma is a mass of normal tissue in an abnormal location - a tumor which ends in blastoma is composed of cells that resemble those seen in a developing organ; most blastomas are malignant - a few tumors of uncertain are named eponymously: Ewing's sarcoma, Hodgkin's disease, Pindborg tumor, Wilms' tumor, Enzinger's sarcoma