Benign VS Malignant Neoplasia Flashcards
Cancer
Malignant neoplasia
Neoplasia
Abnormal and uncontrolled cell proliferation
Irreversible genetic change
Unresponsive to normal controls/growth
Neoplasm
Abnormal mass of tissue that occurs as a result of neoplasia
Mutagenesis
(Initiation)
Introduction of irreversible genetic change to cells by action of a mutagenic initation agent
Oncogenesis
Process by which healthy cells become cancer cells
Cancer develops gradually from normal tissue
Mostly studied in carcinomas (Carcinogenesis)
Benign Neoplasm
Harmless
Don’t invade surrounding tissue
Don’t spread to new anatomic location
Usually curable
E.g. sebaceous adenoma
Pre-malignant Neoplasm
Characterised by malignancy
Once invasion occurs it is considered malignant
Malignant Neoplasm
Cancerous
Invades locally
Spreads by metastasis - distant from primary tumour
Kills animal by interfering with normal body functions
Carcinoma
Malignant neoplasm of epithelial origin
Steps of oncogenesis
Initiation
Promotion
Progression into malignancy
Initiation
(Mutagenesis)
Introduction of irreversible genetic change into normal cells by action of a mutagenic initiation agent
Examples of Mutagenic Initiation Agents
Chemical or physical - e.g. radiation/UV
Inherited or spontaneous
Viruses or bacteria
ROS - Reactive oxygen species
Promotion
○ Outgrowth of initiated cells in response to selective stimulation
○ They drive proliferation
○ Promotors are not mutagenic
Effects are usually reversible
○ Results in benign or pre-neoplastic lesion
Progression into Malignancy
○ Complex and poorly understood process
○ Benign tumour develops into increasingly malignant tumour
○ Malignant tumour may become metastatic
○ Genetic instability + increasing tumour cell heterogeneity
Anaplasia
Lack of cellular differentiation
Differentiation of Benign Vs Malignant Neoplasms
Benign
* Well differentiated
* Similar to tissue of origin
* Little or no anaplasia
Malignant
* Lack of differentiation
* Atypical structure
* Variable anaplasia
Growth Rate of Benign Vs Malignant Neoplasms
Benign
* Slow, progressive
* Rare mitotic figures
* Normal mitotic figures
Malignant
* Slow to rapid growth
* Many mitotic figures
* Abnormal mitotic figures
Local Invasion of Benign Vs Malignant Neoplasms
Benign
* No invasion
* Cohesive growth
* Capsule often present
Malignant
* Local invasion
* Infiltrative growth
* Usually no capsule
Metastasis of Benign Vs Malignant Neoplasms
Benign
* No metastasis
Malignant
* Frequent metastasis
Host Consequences of Benign Vs Malignant Neoplasms
Benign
* Space occupying lesion (effect depends on location)
Malignant
* Life threatening
Host Consequences of Benign Vs Malignant Neoplasms
Benign
* Space occupying lesion (effect depends on location)
Malignant
* Life threatening
Cytological Features of Benign Neoplasms
Minimal - mild anisocytosis
Normal - reduced nuclear:cytoplasmic ratio
Minimal - mild anisokaryosis
Low mitotic count
Minimal or absent necrosis
No individualisation or invasiveness
Cytological Features of Malignant Neoplasms
Marked anisocytosis
Increased nuclear:cytoplasmic ratio
Marked anisokaryosis with frequent binucelation
High mitotic count
Necrosis frequently present
Invasiveness to surrounding tissue including blood and lymph vessels
Mitotic Count
A measure of how fast cells are dividing and growing
