Introduction to Neoplasia: Disorders of Cell Growth Flashcards
What is hypertrophy?
a. Hypertrophy (-trophy means nourishment): increase in size of the individual cells. Ex.
i. Muscular hypertrophy in response to exercise
ii. Gravid uterus during pregnancy (physiologic)
iii. Hypertrophic LV due to increased pressure load (pathologic)
What is hyperplasia?
b. Hyperplasia: increase in size of an organ due to an increase in number of its individual cells Ex.
i. Increase in breast size during pregnancy
ii. Benign prostatic hyperplasia (hyperplastic glands + stroma)
What is atrophy?
d. Atrophy: decrease in size of an organ or tissue that had previously reached its correct size (may or may not be reversible depending on the type of injury) Ex.
i. Muscular atrophy due to disuse of muscle
ii. Cerebral atrophy
What does pathological hyperplasia occur in response to?
i. Repeated tissue injury – relatively uncommon
ii. Increased functional demand – sometimes important
iii. Effect of hormones – most common and important
What is metaplasia?
c. Metaplasia: conversion of one differentiated cell type into another. Ex.
i. Pseudostratified columnar ciliated epithelium in trachea converted to squamous epithelium due to smoking
Clarify the nomeclature of malignant tumours.
o Malignant epithelial: are all called carcinomas
sub-named according to what type of epithelium they come from
* squamous, transitional, basal carcinoma
* adeno- for secretory epithelium. (ex. pulmonary adenocarcinoma)
o Malignant mesenchymal (CT and muscle tissue): sarcoma (ex. liposarcoma)
What is neoplasia?
e. Neoplasia: uncontrolled, abnormal growth of cells or tissues in the body (irreversible)
i. Dysplasia (abnormal growth of cell, but reversible) may lead to neoplasm (cancer)
Distinguish between benign and malignant tumours.
Benign:
* Small
* Well demarcated (some have a capsule)
* Slow growing
* Non invasive
* Non metastatic: localised to the site of origin
* Well differentiated: resemble the tissue of origin
Malignant:
* Large
* Poorly demarcated
* Rapid growing with haemorrhage and necrosis
* Locally invasive
* Metastatic
* Poorly differentiated/completely undifferentiated (anaplastic)
Clarify the nomenclature of benign tumours.
- Benign (suffix – oma)
o Benign epithelial:
Adenoma for secretory epithelium (ex. thyroid adenoma)
Papilloma for exophytic growth (squamous, transitional papilloma)
o Benign mesenchymal (ex. lipoma, chondroma)
What are the categories of grading?
i. Well differentiated
ii. Poorly differentiated
iii. Completely undifferentiated, organs and tissue do not develop past the earliest stages (anaplasia) demonstrate atypia (cellular abnormalities) hallmark for malignancy
1. Pleomorphism: variation in size and shape of cells within the tumour
2. Abnormal nuclear morphology:
a. Disproportionally large nuclei → increase nuclear: cytoplasm ratio
b. Hyperchromasia – darkly staining nuclei
c. Prominent nucleoli
3. Tumour giant cells: large nuclei, sometimes multinucleated
4. Atypical mitoses: atypical, bizarre mitotic figures with tripolar, quadripolar or multipolar spindles. Many cells are in mitosis high degree of proliferation
5. Loss of polarity: orientation of anaplastic cells is markedly disturbed. Loss of normal architecture. Cells grown in an anarchic, disorganised fashion
What is grading?
- Differentiation
a. Definition
i. Biology definition: process by which immature cells become mature cells with specific functions
ii. Cancer definition: describes the resemblance of a tumour cell to the normal parenchymal cell that it came from in both morphology and function
Describe the metastatic cascade (process of metastasis).
- Clonal expansion, growth, diversification, angiogenesis
- Formation of metastatic sub-clones
- Adhesion of these clones to the basement membrane and subsequent invasion
- Passage through the extracellular matrix (proteases)
- Intravasation: invasion of cancer cells through the basement membrane into a blood or lymphatic vessel.
- Interaction with host lymphoid cells and platelets to form a tumour cell embolus
- Adhesion to the basement membrane of endothelium
- Extravasation
- Formation of metastatic deposit
- Angiogenesis
- Growth
What are the 3 pathways for metastasis?
- Lymphatic spread: Epithelial tumours preferentially spread via the lymphatics – hence most common site of metastasis is the lymph nodes for most tumours
- Hematogenous spread: carried by the blood
a. most tumour cells that get into the circulatory system die
b. Metastasis does not occur everywhere blood goes. Blood borne metastasis commonly involves the lungs, liver, kidneys, adrenals, and brain but not the skeletal muscle or spleen.
c. There is no relationship between blood flow (metabolism) and likelihood of metastatic formation. It appears that the targets of metastatic formation are based upon adhesion molecules expressed in vascular beds - Seeding within body cavities (Ex. peritoneal cavity) rare
What is the degree of necrosis in benign vs malignant tumours?
i. Necrosis: consequence of rapid tumour growth
1. In malignant tumours, growth of vascular stroma is often insufficient to supply the tumour → large central areas of ischaemic necrosis (or ulcerative on surfaces – cannot induce the formation of blood vessels on the free surface → necrosis on the free surface → necrotic tissue is removed→ characteristic ulcer with raised edges)
2. Benign tumours often have minimal necrosis
What is a capsule?
a. Benign tumours usually grow and expand slowly, which makes them develop a rim of compressed fibrous tissue called a capsule
i. consists largely of extracellular matrix deposited by stromal cells ex. fibroblasts in response to hypoxic injury from compression by the tumour
ii. Ex.
1. Benign thyroid adenoma exhibits benign expansile growth and is encapsulated. Not harmless as it results in overproduction of thyroid hormone
2. High grade glioma glioblastoma multiforme (GBM)
a. Exhibits predominantly expansile growth – this neoplasm also does not metastasize so is technically benign – but is potentially lethal (rare for benign tumour to be lethal)
b. Growth of brain tissue → increase ICP herniation through foramen magnum → compression of brainstem → death
3. Meningioma with acute, life-threatening haemorrhage (another lethal benign tumour)
