Anatomy and Cancer Flashcards
Define tumour, neoplasm and cancer?
Tumour = general term for any swelling in any part of body, can be benign or malignant.
Neoplasm = any abnormal mass of cells (due to uncontrolled division).
Cancer = malignant neoplasm.
Differentiate between malignant and benign neoplasm.
Benign | Malignant |
| — | — |
| Innocent behaviour | Aggressive behaviour |
| Localised lesion | Can invade local tissues |
| Can affect surrounding tissue by mass effect (compression NOT invasion) | Can spread to other parts of the body (metastasise) |
| Never metastasises | |
What are the 2 basic components of a tumour?
- Tumour parenchyma = clonal expansion of neoplastic cells.
- Supporting stroma = non-neoplastic connective tissue and blood vessels (abundant stroma-desmoplasia).
How are benign tumours classified (broadly)?
Benign tumours are broadly classified based on their cell origin:
- From mesenchyme = benign mesenchymal tumour.
- From epithelium = benign epithelial tumours (based on microscopic or macroscopic elements).
Give examples of benign mesenchymal tumours.
Fibroma, osteoma, leimyoma, angioma.
Give examples of benign epithelial tumours.
Adenoma, cyst adenoma, papiloma, polyp.
How are malignant tumours classified (broadly)?
Also based on their cell of origin:
- From epithelial cells = carcinoma.
- From mesenchymal cells = sarcoma.
Some have more than one parenchymal cell type:
- Mixed tumours = derives from a single germ cell layer that differentiates into more than one cell type.
- Teratomas = derived from more than one germ cell layer and hence composed of many parenchymal cell types.
Describe the major tumour classifications.
Classification depends on clinical behaviour & morphological evaluation.
Categorised based on:
- Degree of differentiation (how close the cancer cell is to a normal cell - look at size, shape, nuclear content, polarity etc).
- Growth rate (fast vs slow growing tumours).
- Local invasion (benign vs malignant).
- Metastasis (can colonise distal structures).
Describe the relationship between growth rate and rate of differentiation.
Degree of differentiation and growth rate are inversely proportional - if growth rate is too fast the cell won’t have time to differentiate and vice versa.
What are the 3 main ways cancer can spread?
- Direct extension/local spread.
- Lymphatic spread.
- Haematogenous spread.
Describe direct extension/local spread.
Tumour extends directly into surrounding spaces.
Invasion of adjacent structure/organs.
Seeding:
- Detachment of cells from primary tumour, spread to surrounding structures.
Give an example of direct local invasion.
Lung cancer → thoracic wall, mediastinum, root of neck.
Bladder cancer → prostate, rectum, uterus, vagina, pelvic side walls.
Give an example of seeding spread.
Peritoneal spread.
Common primaries (primary tumour):
- Gastrointestinal cancers = oesophageal, gastric, colorectal, pancreatic.
- Ovarian cancer.
What is lymph?
Interstitial fluid or the fluid lost from capillary bed.
Describe the pathway of lymph.
- Fluid flows into sinusoids = lymphatic capillary plexus.
- These capillary plexuses come together to form lymphatic vessels (continuous endothelial lining).
- Superficial vessel drain into deep vessels which drain into large lymphatic vessels which drain into lymphatic trunks.
- Both drain into the vena cava.
Where do the 2 main lymphatic trunks drain?
Right lymphatic trunk → right venous angle.
Thoracic duct → left venous angle.
What part of the body does each trunk drain?
Right lymphatic trunk = right upper limb, right part of trunk & head & neck.
Thoracic duct = rest of body.
What makes up the venous angle?
Junction of internal jugular vein and subclavian vein.
Describe the lymphatic spread of cancer.
Cells detach from primary tumour.
Enter lymph capillaries draining adjacent tissues (no functional lymphatics within actual tumour tissue).
Colonise distant tissues - lymph nodes.
What is the first lymph node/group of lymph nodes which cancer spreads to known as?
Sentinel lymph nodes = first lymph node/s draining a tumour.
What are sentinel lymph nodes used for?
Used to predict the likelihood of tumour spread (staging).
Identify sentinel node & take a biopsy.
Example of sentinel lymph nodes.
Commonly used to help stage disease in: breast cancer, colon cancer, melanoma.
What is the sentinel lymph node for breast cancer and how is it identified?
Primary lymph node drainage for breast cancer = axillary lymph nodes.
Identify sentinel lymph node by:
- Blue dye (methylene blue).
- Radioactive tracer (Tc 99).
What is haematogenous spread?
Spread through blood vessels.
