intro to neoplasia Flashcards
what are the types of round cell tumors
- lymphocyte -> lymphoma
- plasma cell -> benign (plasmacytoma) or malignant plasma cell tumor (myeloma)
- mast cell (graded in dogs)
- histiocytic (really benign - histiocytoma, to really bad - histiocytic sarcoma)
- TVT -> dogs, venereal spread
what is a tumor
commonly used term for a neoplasm
- swollen part; swelling, protuberance
- an uncontrolled, abnormal, circumscribed growth of cells in any animal or plant tissue; neoplasm
what is cancer
- malignant and invasive growth or tumor; any disease characterized by such growths
- any evil condition or thing that spreads destructively; blight
what is neoplasia/neoplasm
- “new growth”
- formation or presence of a new, abnormal growth of tissue
- a process in which normal cells undergo irreversible gentic changes, which render them unresponsive to ordinary control on growth
what is oncology
study of neoplasms
what is hamartoma
mass of disorganized tissue indigenous to that particular site. e.g. a mass of adnexal structures in the dermis is an “adnexal hamartoma”
what is choristoma
a mass of normal tissue at an abnormal site, also referred to as a heterotopic rest of cells. e.g. nodule(s) of spleen in the omentum
what is dysplasia
- lack of uniformity of individual cells as well as loss in architectural orientation
- microscopically, there is an abnormality in the maturation of cells within the tissue
- often considered premalignant condition
what is preneoplastic
- changes that may signal an increased risk or likelihood for progression to neoplasia
- these changes are reversible and may arise in reponse to physiologic demands, injury, or irriation, but often resolve when the inciting factor is removed
what are the two basic compnents to all neoplasms, irrespective of whether they are benign or malignant?
- neoplastic cells, determine the biologic behavior of neoplasm
- non-neoplastic stoma, provided by the host, which consists of blood vessels and CT - adequate blood supply is a requisite for cells to live and divide; CT provides the structural framework
what is a benign neoplasm
implies that the neoplasm is considered relatively innocuous based on its gross and microscopic appearance
- localized to a specific site
- cannot and does not metastasize
- amendable to surgical excision
- can produce serious disease and may be life threatening, especially when they arise in the CNS or are functional endocrine neoplasms
naming: mesenchymal benign neoplasms
- attach the suffix -OMA to the cell type to which the neoplasm is differentiating
- fibroblast/cyte -> fibroma
- smooth muscle + OMA = benign neoplasm of smooth muscle
- Leio (smooth) myo (muscle) + OMA = leiomyoma
- fat/lipocyte/adipocyte + OMA = benign neoplasm of fat
- lipo + OMA = lipoma
what is an epithelial neoplasm
based off naming
more complex nomenclaure, based on the microscopic or macroscopic pattern
what is an adenoma
- benign epithelial neoplasm with a glandular pattern or of glandular tissue
- some adenomas may not exhibit neoplasm with a glandular pattern on histopathologic examination
what is a cystadenoma
a benign cystic epithelial neoplasm (apocrine cystadenoma)
what is a papilloma
- a benign epithelial neoplasm growing on an epithelial surface that forms microscopic or macroscopic papilliferous projections (finger-like)
- may be associated with papillomavirus infection
what is a polyp
- a pass projecting above an epithelial surface that forms a macroscopically (grossly) visible structure
- use of the term polyp is best reserved for descriptions of the gross appearance of the mass as in some instances neoplasms can appear polypoid, as can non-neoplastic lesions
what does malignant mean
implies that the neoplasm has the potential to be life threatening by:
- invading and destroying adjacent structures
- spreading to distant sites (metastasize)
how to name a mesenchymal malignant neoplasm
attach the suffix SARCOMA (greek sar = fleshy) to the cell type to which the neoplasm is differentiating
- ex: fibroblast/cyte -> fibrosarcoma
- skeletal muscle + sarcoma = rhabdo + myo + sarcoma = rhabdomyosarcoma
- fat + sarcoma = liposarcoma
- bone + sarcoma = osteosarcooma
- endothelium + sarcoma = hemangiosarcoma
epithelial malignant neoplasm
what is a carcinoma
whether of ectodermal or endodermal origin
epithelial malignant neoplasm
what is an adenocarcinoma
the neoplastic epithelial cells are present in a glandular pattern
epithelial malignant neoplasms
what is a carcinoma in situ
- a pre-invasive stage which does not invade through the basement membrane characterized by severe dysplasia of the epithelial cells
- mitoses above the basal cell layer, nuclear and cellular pleomorphism, darker staining nuclei (hyperchromasia), loss of architectural orientation
what are mixed tumors
- derived from one germ cell layer which undergoes divergent differentiation
- canine mammary tumors: mammary ducts/lobules are made up of inner epithelial cells and outer myoepithelial cells. In some mammary neoplasms both these cell types can be found and if benign called a complex adenoma.
- the myoepithelium may form cartilage and bone called a mixed tumor
- if the epithelial component is malignant then it is a complex carcinoma
- if the epithelial and mesenchymal components are malignant it is called a carcinosarcoma or malignant mixed tumor
what is a teratoma
- arises from totipotential cells, primarily in the ovaries or testis
- cells have the ability to differentiate into any of the cell types found in the adult body, and may give rise to neoplasms that mimic this in a haphazard way
- there are tissues of epithelial, mesenchymal and neural origin within the neoplasm
differentiation in benign vs malignant neoplasms
- benign: well differentiated, resembles tissue of origin
- malignant: often poorly differentiated
local invasion in benign vs malignant neoplasms
- benign: usually cohesive expansile well-demarcated masses that do not invade or infiltrate surrounding normal tissues
- malignant: locally invasive, infiltrating surrounding tissue; sometimes may be seemingly cohesive
proliferation in benign vs malignant neoplasms
- benign: usually progressive and slow; may come to a standstill or regress; mitotic figures rare
- malignant: erratic and may be slow to rapid; mitotic figures may be numerous
metastasis in benign vs malignant neoplasms
- benign: absent
- malignant: sometimes present
what is differentiation
the extent to which neoplastic cells resemble comparable normal cells, both morphologically and functionally
what is anaplasia
- “to form backward” - refers to a lack of differentiation of the neoplastic cells on microscopic examination and implies de-diferentiation or loss of structural and functional differentiation of normal cells
- most cancers do not represent “reverse differentiation” of mature normal cells but arise from stem cells that fail to differentiate
what is pleomorphism
variation in shape and size, refers to the entire cell or nucleus
- anisocytosis and anisokaryosis
- the greater the cellular and nuclear pleomorphism, the less the neoplastic cell resembles the normal differentiated cell, the more anaplastic the cell
anisocytosis
cells of different sizes
anisokaryosis
nuclei of differnt sizes
abnormal nuclear morphology
hyperchromatic
the nuclei of neoplastic cells may contain abundant chromatin and are dark staining
abnormal nuclear morpholoy
karyomegaly
the nuclei are disproportionately large for the cell, and the nucleus-to-cytoplasm ratio is distored may approach 1:1 instead of the normal 1:4 or 1:6
(large nuclei)
morphologic change
mitoses
- undifferentated neoplasms usually have large number of mitoses, reflecting the higher proliferative activity
- the presence of mitoses does not necessarily indicate that a tumor is malignant or that the tissue is neoplastic
- malignant neoplasms often have atypical, bizarre mitotic figures
- mitotic index is a good indication of the growth rate and malignant potential of a neoplasm
morphologic changes
polarity
- orientation of anaplstic cells is markedly distribited (lose normal polarity)
- sheets or large masses of tumor cells grow in a hapharzard or disorganzied fashion
morphological changes
function
- the more anaplastic the neoplasm the less likley it is to retain its specialized functional activity
- some non-endocrine cancers produce hormones - a condition known as paraneoplastic syndrome
- most common is hypercalcemia due to the synthesis of PTHrP by neoplastic cells
what is desmoplasia
some neoplasms stimulate the formation of an abundant collagenous stroma by the host, feels very firm or scirrhous
what is carcinomatosis
- transcoelomic spread or seeding
- occurs when cancers invade and seed a natural body cavity and re-impant at distant sites within the cavity
- commonly seen with carcinomas of the ovary, GI tissue and lung
what is lymphatic spread
- found with carcinomas
- primary carcinoma is most likley to spread to the regional lymph node(s)
- from regional nodes it spreads to other nodes and then enters the blood stream via the thoracic duct, which empties into the vena cava
- neoplastic cells become trapped in pulmonary capillaries and grow in lung tissue
what is hematogenous spread
- found with sarcomas
- occurs by invasion of veins or venules by the cells of the primary neoplasm
- the neoplastic cells follow the venous flow draining the site of the neoplasm
- lungs and liver are the most commonly involved sites
what is venereal spread
- unique and is found in the dog
- transmissible venereal tumor
- transmission occurs only by transplantation of viable neoplastic cells during coitus
what is metastasis
the development of secondary neoplasms at sites distant from the primary neoplasm
proliferation
what are the 3 factors that determine rate of growth
- doubling time of tumor cells
- fraction of tumor cells that are in the replicative pool
- rate at which cells are shed or die
what are the important implications of cancer stem cells
- cells must be eliminated to cure patients
- cells likley have high intrinsic resistance to conventional therapies because of their low rate of cell division and expression of factors which as MDR-1
