Topics A53-57. Neoplasm 1: General characteristics, Histology Classification, Growth Rate, Invasion, Metastasis Flashcards
Neoplasm definition
Simple definition: Abnormal mass or tissue, “new growth”
Other descriptions:
- Uncontrolled cell growth which exceeds normal tissue
- Genetic abnormality of cell which is passed to daughter cells
- Autonomous growth, independent from factors like hormones
What 2 things are neoplastic tissue composed of?
- Parenchyma: neoplastic cells
- Stroma: connective tissue that is non-neoplastic but provides support, blood supply
(basically the same as any other tissue)
The big one: What are the 10 biological features of neoplastic tissue?
- Autocrine growth
- Resistance to apoptosis
- Limitless capacity for growing/division
- Loss of cell differentiation
- Inducing angiogenesis
- Invasion into tissues
- Metastases
- Remodeling of Metabolic Pathways
- Insensitivity to Growth Signal Inhibitors
- Evades the immune system
What is a benign tumor?
A tumor with “favorable clinical behavior” - localized, doesn’t invade surrounding tissue, does not metastasize.
After surgery, there is no recurrence of benign tumors. They are usually encapsulated.
Benign tumor cells are usually more differentiated than malignant cells
What is a malignant tumor?
A tumor with aggressive behavior. Grows rapidly, invades the surrounding tissue, provides metastases. The cells are poorly differentiated - do not resemble normal parenchymal cells.
Likely to reappear after surgery.
What is an example of a tumor that cannot metastasize yet is still very dangerous? (blurs the definitions of benign and malignant)
Glial cell tumors: primary brain tumors that cannot get outside of skull, but can still be aggressive and dangerous
What are the 2 “semi-malignant” tumors? Why do they fit this definition?
- Basal cell carcinoma / basolioma: invades tissue locally, but after surgery there is no recurrence (really know this one because Hungarian from this dept first identified it, also this is the most common cancer)
- Pleomorphic adenoma: a salivary gland tumor that is benign and encapsulated, yet recurs after surgery because it has protrusions along the nerves that are not easily removed
What is the most-used example of a “borderline” tumor?
What is a borderline tumor?
Ovarian cystadenoma: epithelial tumor over the ovary. Epithelial cells do not invade the deep ovarian tissue, so it’s similar to malignant but with no invasion. May be the early phase of neoplasm.
Borderline tumors are ones whose behavior cannot be predicted by morphological presentation - mostly they don’t metastasize, but sometimes they do.
What suffix do benign tumors usually get?
What suffix do malignant tumors usually get? (3 kinds)
Benign: -oma
Malignant:
- carcinoma (epithelial)
- sarcoma (mesenchymal)
- teratocarcinoma (germ cell)
How do you call benign tumors of:
- Epithelium
- Mesenchyme
- Germ cell
- Epithelial: adenoma
- Mesenchymal: depends on origin (e.g. hemangioma, osteoma, fibroma)
- Germ cells: teratoma
What are 3 exceptions to the -oma suffix where it’s used for malignant tumors instead of benign? (and it’s not part of longer suffix like carcinoma, sarcoma)
- Lymphoma: only malignant, never benign
- Melanoma: also always malignant (benign = nevus)
- Astrocytoma, Glioblastoma: glial tumors named by their anatomical location more than histo appearance. Gliobastoma is high grade form.
What are the 4 different classifications of lymphoma?
- Low-grade lymphoma
- High-grade lymphoma
- Hodgkin lymphoma
- Non-Hodgkin lymphoma
What is a polyp?
A mass that projects from a mucosal surface. Can be benign or malignant
What is a hamartoma?
Non-neoplastic, disorganized, tumorlike overgrowth of cell types regularly found within an affected organ
Example: Hemangioma - an irregular accumulation of blood vessels
What is anaplasia?
Loss of differentiation. The neoplastic cells are pleomorphic: their size and shape are variable.
Maturation is blocked, they have abnormal nuclear morphology. Atypical mitosis occurs. May look vacuolar.
Cells lose their function and also polarity: e.g. epithelial layers are completely disoriented
How differentiated are the cells in these neoplasms:
- Benign
- Malignant
- Semimalignant
- Borderline
- Benign: look mostly differentiated
- Malignant: Variable: often lose their differentiation
- Semimalignant: Mostly differentiated
- Borderline: Mostly undifferentiated