T24 - General Principles of Tumorigenesis Flashcards
Define tumor.
swelling or mass
Does a tumor imply cancer?
No. The presence of a tumor indicates the possibility of a malignancy, but does not imply cancer.
What is a neoplasm?
biological process of cellular growth in which a group of cells grows faster than its neighbors
How would a neoplasm arise?
if a group of cells acquires somatic (i.e. not inherited) mutations that confer growth advantage
What is a precancer?
microscopic neoplasm that does not yet form a tumor
What is the precursor to cervical cancer?
cervical intraepithelial neoplasia (CIN), a microscopic neoplasm
What is a cancer?
neoplasm/neoplastic process in which cells have acquired ability to spread locally (invasion) or systemically (metastasis)
What is a synonym for cancer?
malignancy
Cells in a healthy liver do not divide very much. Under what conditions would cell proliferation increase in hepatocytes?
a partial resection (partial hepatectomy) would induce remaining hepatocytes to quickly proliferate and regrow the lost part of the organ
In the context of neoplasms, what is disequilibrium?
cell growth exceeds cell death, resulting in progressive (but not necessarily indefinite) growth
Explain why most malignant neoplasms have both increased cell growth and increased cell death. (2)
deregulated cell growth triggers apoptosis, and normal apoptotic checkpoints are only partially affected in cancer
however, rate of cell growth outpaces rate of cell death
What are the two defining features of neoplasia?
disequilibrium (cell growth > cell death)
uncoordinated growth
What is contact inhibition?
a physiological stimulus that places limits on cell growth
Explain the relationship between neoplasia and contact inhibition.
neoplasms are no longer responsive to physiological stimuli such as contact inhibition that place limits on their growth
What is hyperplasia? (2)
overgrowth of tissue in response to stimulus for growth
hyperplasia ends once stimulus ends
What are key differences between hyperplasia and neoplasia?
manner of growth:
hyperplasia = coordinated growth and normal architecture
neoplasia = uncoordinated growth and abnormal architecture
mutations vs. stimuli:
neoplasia = results from genetic mutations that allow it to bypass regulatory mechanisms
hyperplasia = impetus for growth arises externally (not internally)
Describe the relationship between neoplasia and hyperplasia.
hyperplasia provides fertile ground for neoplasia
long-standing hyperplasias can become neoplasia-like (but will have more ordered growth)
some neoplasms depend on stimuli
What is the relationship between neoplasia and metaplasia? (2)
metaplasia is also a fertile ground for neoplasia because of a carcinogenic stimulus or because of associated hyperplasia
Dysplasia refers to
abnormal cytoarchitecture and disarrangement of cells seen microscopically
Most cancers arise from which tissue of the body?
most cancers arise from epithelia
How is dysplasia recognized histologically?
loss of normal, progressive maturational sequence
cellular atypia
loss of normal tissue organization
What is cellular atypia?
atypical appearance of cells in a tissue section
What is the relationship between dysplasia and precancer?
dysplasias are a form of precancer (they can either progress into cancers or not)
What is carcinoma in situ?
lesion that histologically cannot be distinguished from cancer cell, but has not transgressed normal tissue boundaries
What is a Pap smear?
examination of exfoliated surface cells from cervical epithelium that can detect all grades of dysplasia
You perform a Pap smear on a patient. Histological analysis detects a dysplasia in situ. What happens next? (2)
recommend for minimally invasive surgery (the “cure”) to remove the tissue with dysplastic cells
minimally invasive surgery option applies as long as dysplasia remains in situ
Describe the reversibility of dysplasias.
dysplasias can regress spontaneously or progress into invasive cancer
Explain the relationship between epithelial dysplasia and neoplasia.
most forms of epithelial dysplasia are neoplasms confined to epithelium
What is histogenesis?
type of differentiation exhibited by tumor cells
What is the first/most basic distinction made in tumor classification?
whether the cells are of epithelial or mesenchymal histogenesis
What are adenomas?
benign tumors derived from glandular epithelium
(T/F) All adenomas, by definition, are benign.
False. Some types of adenomas are not truly benign.
Most adenomas are benign, but some are not. Give an example of an adenoma that is not truly benign.
colonic adenoma — example of dysplasia that tends to form a tumor (visible polyp), even though there is no stromal invasion
Differentiate between colonic dysplasia and cervical dysplasia in terms of how they are observed.
colonic dysplasia forms a grossly visible polyp
cervical dysplasia is invisible to the naked eye
Describe the basis of “mucinous cystadenoma of the ovary.”
adenoma of mucin-producing epithelial cells, where the ovary contains multiple large cysts filled with mucin
Describe the basis of the name “serous cystadenoma of the ovary.”
made up of non-mucinous cells that form cysts filled with watery fluid
What is an exception to the adenoma naming convention?
papillary glandular tumors are just called papillomas
True polyps are the result of
abnormal surface epithelial growth
What are polyps?
common neoplastic growth pattern in surface epithelia
attached through stalk
What is papillary architecture?
common pattern of abnormal growth in surface epithelia lining cavities and ducts characterized by complex branching
Give three examples of papillomas.
squamous cell papilloma of skin (a.k.a. skin tag)
transitional cell papilloma of bladder
intraductal papilloma of breast
What is a melanocytic nevus? (2)
benign tumor of dermal melanocytes
also called just a “nevus”
Tumors that end in “-oma” can be benign or malignant. List two malignant variants.
mesothelioma
hepatoma = hepatocellular carcinoma
Malignant epithelial tumors, in general, are known as
carcinomas
Generally speaking, what are carcinomas?
malignant epithelial tumors
Differentiate between carcinomas and adenocarcinomas.
adenocarcinomas are carcinomas (malignant epithelial tumors) that derive from glandular epithelium (breast, colon, prostate, endothelium)
What happens to the term “adenocarcinoma” when it is modified by its tissue of origin?
when modified by tissue of origin, “adenocarcinoma” loses “adeno” part and is just called a “carcinoma”
Give three examples of adenocarcinomas that lose the “adeno-“ prefix when modified by tissue of origin.
renal cell carcinoma
colon carcinoma or colon adenocarcinoma
hepatocellular carcinoma
What is the naming convention for benign mesenchymal neoplasms?
names reflect histogenesis/cell of origin, followed by “-oma”
What is a fibroma?
mesenchymal tumor with fibroblast differentiation
Lipoma involves
fat
Chondroma involves
cartilage
Osteoma involves
bone
Hemangioma involves
blood vessels
Lymphangioma involves
lymphatics
Leiomyoma involves
smooth muscle
Rhabdomyoma involves
skeletal muscle
Meningioma involves
meninges
What is the naming convention for malignant mesenchymal tumors?
cell of origin + “-sarcoma”
What are four exceptions to the tumor/neoplasm naming rules?
malignant peripheral nerve sheath tumor (MPNST) = malignant schwannoma
leukemia
lymphoma
invasive meningioma
[MILL]
What is a malignant peripheral nerve sheath tumor, also known as a malignant schwannoma?
malignant tumor of Schwann cells in peripheral nerves
What is leukemia?
tumor of white blood cells with circulating neoplastic cells
What is a lymphoma? (2)
tumor of white blood cells that forms masses in lymph nodes
may have circulating neoplastic cells
What is an invasive meningioma?
aggressive, invasive version of typically benign meningioma
What are three tumors that cannot be categorized based on epithelial vs. mesenchymal origin?
seminoma
melanoma
carcinoid tumor
What is a seminoma?
malignant tumor of germ cells (i.e. testicular cancer)
What is a melanoma?
malignant tumor of melanocytes
What is a carcinoid tumor?
a tumor derived from neuroendocrine cells that often arises in the gut
What are mixed tumors?
tumors comprised of admixed epithelial and mesenchymal components
What is a synonym for mixed tumor?
biphasic tumor
On a cellular level, how do mixed tumors differ from monophasic tumors?
mixed tumors have two or more types of neoplastic cells, whereas monophasic tumors only have one type of neoplastic cell
Give two examples of benign mixed tumors.
pleomorphic adenoma
fibroadenoma
What is a pleiomorphic adenoma? (2)
tumor w/ neoplastic epithelial and stromal elements
found in salivary gland
What is a fibroadenoma? (2)
tumor w/ neoplastic epithelial and stromal elements
found in breast
Give four examples of malignant mixed tumors (with two cell types).
malignant mixed tumor of salivary gland (malignant version of pleomorphic adenoma)
Wilms tumor (kidney)
mixed mullerian tumor = carcinosarcoma of uterus
cystosarcoma phyllodes of breast
What are teratomas?
tumors composed of 3 or more cell types
Teratomas typically arise from
toti- or multi-potent cells — in other words, they arise from germ cell lineage
In which tissue structure(s) are teratomas observed? (2)
most often, observed in gonads
but can arise in extragonadal locations due to aberrant migration in embryogenesis (i.e. brain, mediastinym)
Give two examples of benign teratomas.
mature teratoma (cells resemble those in mature, adult tissues)
dermoid cyst
What is a dermoid cyst?
mature teratoma characterized by keratinaceous debris formed from desquamating squamous epithelial cells
Give an example of a malignant teratoma.
immature teratoma (cells resemble primitive cells in embryonic development)
Define hamartoma.
malformation that resembles neoplasm but actually results form focal maldevelopment of that organ
A hamartoma consists of
tissue elements normally found at that site
What is a choristoma?
tumor formed by maldeveloped tissue not normally found at that site
Give a common example of a hamartoma.
pulmonary hamartoma (typically composed of cartilage + bronchial epithelium)
What is another name for a choristoma?
heterotropic rest
Give an example of a choristoma/heterotropic rest.
adrenal rest
What are adrenal rests?
harmless small masses of adrenal tissue found near ovary or kidney
Are hamartomas and choristomas malignant?
No. By definition, both hamartomas and choristomas are benign.
What is the primary difference and primary similarity between the terms “carcinoma” and “sarcoma?”
carcinoma = epithelial origin, whereas sarcoma = mesenchymal origin
both carcinoma and sarcoma imply malignancy
(T/F) Hamartomas and choristomas are classified as neoplasms.
False. Hamartomas and choristomas are classified as non-neoplastic malformations.
(T/F) Cancers do not have to metastasize to be lethal.
True.
Give an example of contact inhibition that is commonly observed in laboratories.
fibroblasts can be cultured in a petri dish but will stop dividing after reaching a certain density
What is the difference between neoplasia and hyperplasia in the context of the term “clonal?”
neoplasms derived from a single, genetically abnormal cell (monoclonal) — outgrowth of this abnormal cell
hyperplasias are polyclonal outgrowths of genetically normal cells
Leukemias and lymphomas are derived from what kind of cell?
hematopoietic cells
What is the most common type of germ cell tumor?
mature teratoma
(T/F) Neoplasms are malignant.
False. Not all neoplasms are malignant.
What is the “grey zone” between hyperplasia and neoplasia?
hyperplasia can lead to neoplasia because more growth means more opportunities for mutations
MALT lymphoma is the result of
an H. pylori infection
(T/F) Metaplasia is irreversible.
False. For example, you can treat Barrett’s esophagus if you catch it early enough.
What is the relationship between carcinoma in situ and just a regular carcinoma?
carcinoma in situ means that the neoplasm has not crossed the basement membrane
Differentiate between adenomas and papillomas.
adenomas = glandular and have a more blob-like shape
papillomas = non-glandular and have a finger-like shape
Cystadenomas can produce what two products?
mucinous products
serous products
What do HSIL and LSIL stand for?
high/low grade squamous intraepithelial lesion
