Neoplasia Flashcards
What is neoplasia?
- “new growth”
- benign or malignant
- oncology = study of tumours or neoplasms
- cancer = malignant neoplasia
- benign neoplasms are not cancer!
Components of a tumour (2)
1) parenchymal cells/neoplastic cells (determines classification and biologic behaviour)
2) Reactive stroma (plays key role in determining growth and spread of tumour; desmoplasia = occurs surrounding neoplasm, causing dense fibrosis/scar tissue)
Benign and Malignant tumours (features of each)
Benign:
- Remains localized (does not invade into surrounding tissues/organs; doesn’t metastasize to other parts of body)
- Usually amenable to surgical removal
- Patient usually survives
Malignant:
- Has the capacity to invade into surrounding tissues/through the basement membrane
- Has the potential to metastasize to different locations in the body
Classification of tumours (4)
- Benign or Malignant
- What body site/organ of origin
- What tissue type (epithelial, mesenchymal)
- What cell type (squamous, glandular)
Epithelium
- lines external and internal surfaces
- cells closely packed together and polarized
- classified by 1) cell shape 2) cell layers
- attached to connective tissue through basement membrane
Mesenchymal
- from embryological layer, from mesoderm
- makes connective tissue (cartilage, bone, fat, blood cells)
- loose and dense fibrous tissue
- made up of cells and extracellular material
- endothelial cells
Nomenclature for benign tumours
Benign mesenchymal tissue tumours:
- oma
Benign epithelial tissue tumours:
1) adenoma
- benign tumour arising from gland or lining of gland (doesn’t have to form a gland, although some do)
2) papilloma
- benign tumour composed of projections with fibrovascular core covered in epithelium
3) cystadenoma
- benign tumour that forms a cystic mass
Nomenclature: name each type of tumour BENIGN: fat cartilage bone blood vessels smooth muscle striated muscle glands/ducts squamous transitional (urinary tract)
- lipoma
- chondroma
- osteoma
- hemangioma
- leiomyoma
- rhabdomyoma
- adenoma
- papilloma
- cystadenoma
- squamous cell papilloma
- transitional cell papilloma
Nomenclature for malignant tumours
mesenchymal tissue: sarcoma
epithelial tissue: carcinoma
- when unknown: undifferentiated malignant tumour, tumour of unknown primary…
Nomenclature: name each type of tumour MALIGNANT: fat cartilage bone blood vessels smooth muscle striated muscle glands/ducts squamous transitional (urinary tract)
- liposarcoma
- chondrosarcoma
- osteosarcoma
- Angiosarcoma
- leiomyosarcoma
- rhabdomyosarcoma
- adenocarcinoma
- papillary carcinoma
- cystadenocarcinoma
- squamous cell carcinoma
- transitional cell carcinoma
Nomenclature
- primitive malignant neoplasms
- blastoma
- typically pediatric malignant neoplasms showing primitive/embryonal history
- e.g. nephroblastoma (Wilm’s tumour)
Nomenclature:
- mixed tumours
- benign pleomorphic adenoma of salivary gland
- malignant mixed mullerian tumour (MMMT, carcinosarcoma): mix of endometrial carcinoma and sarcomatous carcinoma
- teratoma (monster tumour: more than one germ lines, benign or malignant, from germ cells)
Nomenclature exceptions and eponymous neoplasms
malignancies with benign sounding names:
- Lymphoid tissue: Lymphoma
• Melanocytes: Melanoma
• Mesothelial cells: Mesothelioma (pleural space in lungs)
• Germ cells: Seminoma/Dysgerminoma
• White blood cells: Leukemia
• CNS: Astrocytoma, oligodendroglioma, etc.
Eponymous Neoplasms
• Ewing’s sarcoma (bone malignancy in younger ppl)
- Kaposi’s sarcoma (malignant, blood vessels)
• Warthin’s tumour (salivary gland, benign)
- Brenner tumour (ovary, usually benign)
Congenital benign tumours
Hamartoma
• Disorganized but benign mass of tissue composed of
cells indigenous to that site
Choristoma (gastric epithelium in intestine)
• A heterotopic rest of normal tissue at an abnormal
location
• Usually a congenital anomaly of little if any significance
Polyp (bump above epithelium) (benign, malignant, or dysplastic) (lots of polyps in the colon)
• A macroscopically visible projection above a mucosa
surface (may be benign or malignant)
E.g., Tubular adenoma of colon:
• Benign tumour of colonic glandular epithelium by
nomenclature rules
Actually a low‐grade dysplastic lesion
• Clinical behaviour is benign at this stage, but has
potential to evolve into colonic adenocarcinoma
(so nomenclature is wrong; nomenclature says benign, but it can become malignant, so it’s wrong)
Characteristic differences of benign and malignant tumours
- Rate of growth
- Precursor lesions
- differentiation and anaplasia
- local invasion
- metastasis
Rate of tumour growth
- not the best determinant of malignancy
- generally, malignant tumours grow faster
- but there is a lot of diversity in malignant tumour growth (some really fast, some slow)
- abnormal mitotic figures never seen in benign tumours
Differentiation and anaplasia
differentiation: the extent to which neoplastic cells resemble their original cells (functionally and morphologically)
- benign tumours are usually very well differentiated
- malignant tumours range from well differentiated to poorly differentiated
Anaplasia: lack of differentiation
Poor differentiation/anaplasia is associated with:
- pleomorphism
- abnormal nuclear morphology
- loss of polarity and architecture
- mitoses (atypical/bizarre)
- necrosis (used up blood supply)
Anaplastic characteristics:
- high N:C ratio
- irregular nuclear border
- large nucleolus
- hyperchromasia (darkly stained due to lots of DNA)
Precursor lesions
hyperplasia: associated w increased dysplasia risk
hypertrophy: not associated w increased cancer risk
metaplasia: associate with increased dysplasia risk
Dysplasia: just like malignant morphology, but it DOESN”T INVADE BASEMENT MEMBRANE (not malignant; pre-malignant)
dysplasia isn’t a benign tumour - it has the ability to become malignant
local invasion
benign: smooth, encapsulated, no invasion, easy to take out
malignant: destructive invasion of surrounding tissue (desmoplasia)
no clear plane of destruction
no anatomical border respect
irregular border around tumour (harder for surgical removal, may need large margin)
metastasis
1) lymphatics (most common)
2) blood (typical for sarcomas, possible for carcinomas). most common way to get to liver and lungs (blood)
3) direct seeding (rarest)
tumour grade and stage
GRADE
- degree of differentiation present
- to what extent it resembles original cells
- low-grade: still well differentiated
- high-grade: poorly differentiated
STAGE:
extent of spread of cancer (determined by combination of surgery, histology, and imaging)
AJCC staging thing
TNM
tumour size and extent of local invasion (T0-T4)
nodes: how many lymph nodes (N0-N3)
metastasis: yes or no (M0-M1)
