Neoplasia Flashcards
Define cancer?
Genetic disorder caused by mutations that are acquired spontaneously or through environmental insult. Cancers show increased DNA methylation and histone modification. These mutations alter growth, survival and senescence. These mutations are also heritable.
What are the hallmarks of cancer?
1) Self-sufficiency in growth signals;
2) Lack of response to growth inhibitory signals;
3) Evasion of cell death;
4) Limitless replicative potential (immortality);
5) Angiogenesis to maintain growth;
6) Ability to metastasise;
7) Reprogramming of metabolic pathways (e.g aerobic glycolysis);
8) Ability to evade immune system.
What does the suffix -oma denote? What are the types?
It implies a benign tumor.
Fibrous tissue - fibroma;
Cartilaginous - chondroma;
From gland patters and glands - adenoma;
On surfaces with finger like fronds - Papilloma;
Above a mucosal surface - polyp;
Hollow cystic masses - cystadenoma;
What are sarcomas?
Malignant neoplasms in solid mesenchymal cells and their derivatives.
What are leukaemias / lymphomas?
Malignant neoplasms of mesenchymal cells of the blood.
What is the importance of stromal cells in the development of a neoplasm?
Carries blood supply and provides support and growth to parenchymal cells?
What are the subdivisions of carcinomas (epithelial)?
Adenocarcinoma (glandular), squamous cell carcinoma, can be named based on effected organ and poorly differentiated / undifferentiated.
What is the most common mixed tumor that arises through divergent differentiation?
Mixed tumor of the salivary gland - epithelial components through fibromyxoid stroma (possibly containing cartilage or bone). They are derived from epithelial and myoepithelial cells, therefore termed polymoprhic adenomas).
What is the term given to the mixed tumor containing proliferating ductal elements contained within neoplastic fibrous tissue?
Fibroadenoma
What is a teratoma?
Mixed tumour that contains cells or tissue representative of one or more germ cell layer form totipotent germ cells such as those in the testes or ovaries (sequestered midline embryonic rests).
What is a hamartoma?
Disorganised tissue involving indigenous tissue - possibly developmental malformation; but evidence of translocations (neoplastic).
What is a choristoma?
Congenital heterotopic rest of cells - i.e cells are in the wrong place (pancreas cells / tissue in intestines). Of trivial significance.
What are the exceptions to the nomenclature regarding benign and malignant cells? i.e which cancers have the suffix -oma but are malignant?
Lymphoma, mesothelioma, melanoma and seminoma.
What feature of benign tumors means that they rarely develop into malignancy?
The fact that benign tumours change little in genotype over time.
What are the four criteria on which the benign or malignant nature of a tumor are determined?
Differentiation and anaplasia, rate of growth, local invasion and metastasis.
Is the neoplasm seen in well differentiated cells in which mitosis is rare and in the normal configuration benign or malignant?
Benign.
Is the neoplasm seen in undifferentiated cells (or moderately well differentiated cells) benign or malignant?
Malignant.
What difficulty may arise in classifying a tumor as benign or malignant based on cell differentiation?
Some malignant tumors are well differentiated.
Though thickness of the stroma does not help with classifying tumors (as it is necessary for the growth of all neoplasms) what does it determine?
The thickness of the stroma determines the consistency of the tumor as some cancers result in a thick fibrous stroma (desmoplasia) and are termed scirrhous).
What is the term given to undifferentiated neoplasms?
Anaplasia - dedifferentiation of cells. Some cancers arise from proliferation of stem cells which fail to differentiate as well.
What are the pleomorphisms displayed by anaplastic cells?
Large hyperchromatic nuclei; giant cells with a large / multiple nuclei; coarse, clumped chromatin; large nucleoli; mitoses are numerous and atypical (due to multiple spindles there may be tripolar or quadripolar mitotic figures; loss of polarity.
What are some un-anticipated functions of well differentiated cancer?
Elaboration of foetal proteins (ectopic hormones from nonendocrine origin) e.g release of ACTH, parathyroid hormone, insulin, glucagon etc from lung carcinomas.
What is dysplasia?
Non-neoplastic disorder of cells losing uniformity in architectural orientation displaying many of the same pleomorphisms seen in anaplasia.
What is special about the mitosis seen in dysplasia of the epithelium?
Mitosis can be observed in all germ layers not just the basal layer - disorder fo scrambling dark basal appearing cells (squames).
What is carcinoma in situ?
Marked dysplastic changes involving the entire epithelium (preinvasive stage of cancer).
If the inciting cause of a mild or moderate dysplasia that does not involve the entire epithelium is removed can complete regression occur?
Yes
What factors affect the rate of growth of a tumor (benign or malignant)?
Level of circulating hormones (oestrogen leads to rapid growth of leiomyomas of the uterus); blood supply; pressure constraints (adenomas of pituitary gland constrained by the sella turcica - necrosis due to compressed blood supply).
What is the relationship between the rate of growth of a malignant tumor and its level of differentiation?
Rate of growth is inverse proportional to level of differentiation.
What would cause a relatively slow growing tumor to suddenly begin growing rapidly?
Emergence of an agressive subclone of transformed cells.
Why do rapidly growing malignant tumors often contain a central area of ischaemic necrosis?
Tumor blood supply fails to keep up with oxygen needs of expanding cell mass?
What is the function of stem cells in a tumor?
As there is continues growth of short lived cells such as blood elements and epithelial cells a population of long-lived and self - renewing stem cells are required.
How are stem cells sustained in tissues?
Paracrine factors secreted by support cells.
What features indicate that tumors must contain cells with stem like properties?
The immortality provided by the fact that stem cells divide asymetrically into cells with limited proliferative potension and those that maintain stem cell potential.
What are the implications for cancer treatment posed by the presence of stem cells in tumors?
To cure a cancer one must eliminate the immortal stem cells; as stem cells express factors such as multiple drug resistance - 1 they are resistant to chemotherapeutic drugs.
How does the capsule around an adenoma develop?
It is formed by the stroma of the host tissue as the parenchymal cells atrophy under pressure as well as the stroma of the tumor.
What type of cleavage place in present around leiomyoma of the uterus?
A zone of compressed and attenuated normal myometrium.
In which benign tumor is demarcation unlikely to be seen?
In vascular neoplasms of the dermis.
