Neoplasia 1 Flashcards
-Define neoplasia -Differentiate a true neoplasm from other growths -List the changes which may precede neoplasia -List the important veterinary tumour types based on cells of origin -Differentiate between benign and malignant tumours using the relevant features: differentiation and anaplasia, rate of growth, local invasion and metastasis.
NEOPLASM
“New growth”
CELLS ARE UNRESPONSIVE TO NORMAL GROWTH CONTROLS.
They are able to expand outwith their normal anatomical boundaries; there is increased dispersal around the body.
ANAPLASIA
No differentiation of cells
HAMARTOMA
NON NEOPLASTIC
Tissue is chaotically arranged, but is IN AN APPROPRIATE SITE.
CHORISTOMA
NON NEOPLASTIC
Tissue is chaotically arranged, in an ABNORMAL site.
eg. Dermoid- normal mature haired skin is seen on the cornea of the eye.
The skin has not properly differentiated to it’s final form (corneal epithelium) -> irritational conjunctivitis.
ARE LUMPS ALWAYS TUMOURS?
NO. They could be abscesses, and multiple lumps are not always caused by the same thing.
eg. 2 enlarged adrenal glands- one enlarged due to benign nodular hyperplasia (normal part of aging), the other is red and swollen- it may be aplastic.
ARE TUMOURS ALWAYS LUMPS?
NO! Sometimes, primary lesions can be skin ulcerations etc, then secondary neoplasia/metastasis can be seen elsewhere in the body. eg. nodules in the liver.
CHANGES WHICH MAY PRECEDE NEOPLASIA
Preneoplastic changes are reversible, arise in response to physiologic demands, injury or irritation and will REGRESS if the inciting factor is removed. They are not always pathogenic. -HYPERPLASIA -HYPERTROPHY -METAPLASIA -DYSPLASIA
HYPERPLASIA
Increased NUMBER of cells.
eg. Gingival hyperplasia. Gum overgrowth affects 30% of boxers over 5 years. Great Dane/Dobermann also.
Not neoplastic but can cause functional problems- bleeding, pain on eating, regrowth on removal.
Cyclosporin and phenytoin can induce this hyperplasia.
eg. Sebaceous hyperplasia. Dome shaped/papillated masses usually seen on head. Non neoplastic; no evidence of cellular invasion of deeper tissues (on histology), sebaceous glands are hyperplastic.
Can become neoplastic- GLANDS LOST, TISSUE BECOMES MORE JUMBLED, INVASION OF UNDERLYING TISSUE.
HYPERTROPHY
Increased SIZE of cells.
METAPLASIA
One type of differentiated cell changes to another.
This is a PRECEDING FACTOR for neoplasia.
DYSPLASIA
Cells lose polarity and thus become ‘mixed up’ and disarranged.
PROSTATIC HYPERPLASIA
Can be benign or malignant.
Even benign enlargement (most common cause of prostatic enlargement in older intact male dogs) can cause functional problems.
Enlarged prostate pushes up on colon, restricting passage of faeces.
-Difficulty defaecating/urinating
-May see blood in urine.
VETERINARY TUMOUR GROUPINGS
- MESENCHYMAL (mesoderm)
- Connective tissue, fat, cartilage.
- Endothelium and related tissue.
- Muscle.
- Haematpoietic and lymphoid tissue (bone marrow, spleen/liver in sick animal) - EPITHELIAL (endoderm/mesoderm/ectoderm)
- Ectoderm- covering epithelium (eg. skin)
- Mesoderm- solid organs (eg. renal tubules, hepatocytes)
- Endoderm- lining epithelium (eg. GI mucosa) - NERVOUS TISSUE- CNS and PNS
-Glial cells
-Neural cells
Both types of cell can form tumours; tumours can be mixed. - MIXED- Divergent differentiation of monoclonal cells (eg. mammary gland- often see cartilage/bone, ovary, testis)
- UNDIFFERENTIATED- poor prognosis.
MESENCHYMAL TUMOURS
BENIGN: “-oma”
MALIGNANT: SARCOMA.
eg. a tumour of adipocytes from fat will be called a lipoma if it is benign, or a liposarcoma if it is malignant.
EPITHELIAL TUMOURS
BENIGN “-oma”
MALIGNANT: CARCINOMA
eg. a tumour of skin squamous epithelial cells will be called a squamous papilloma if it is benign, or a squamous cell carcinoma if it is malignant.
