Neoplasia Flashcards
Neoplasm definition and distinguishing features:
Abnormal growth of cells which persists after initialising stimulus removed
Distinguishing features:
- Differentiation
- Rate of growth (malignant fast growing, benign slow growing)
- Local invasion
- Metastasis
Benign vs malignant
Malignant: A neoplasm with potentially lethal, abnormal characteristics which has the ability to invade metastasise
Benign: A neoplasm which does not have the above ability
What is differentiation, and what is meant by well/poor/undifferentiated differentiation?
The extent to which neoplastic tissues resemble their normal tissue of origin
Well differentiated:
- Closley resembles tissue of origin
- E.g Benign tumours
Poorly differentiated:
- Little resemblance of tissue of origin
- Variation in nuclear shape/size
- E.g Malignant tumours
Undifferentiated: Cannot be identified without molecular techniques
Benign and malignant suffixes for epithelial tumours:
Benign - OMA:
- Adenoma (glandular tissue)
- Papilloma (cell type)
- Identified by cell type and glandular tissue (e.g. squamous cell papilloma / colonic adenoma)
Malignant - Carcinomas:
- Adenocarcinoma (glandular tissue/degree of differentiation)
- Carcinoma (cell type)
Benign and malignant suffixes for mesenchymal tumours:
Benign - OMA (examples):
- Bones - osteoma
- Fat tissue - lipoma
Malignant - Sarcoma:
- All types have this suffix
- E.g fat tissue = liposarcoma
Hamartomas and choristomas
Hamartoma: Non-neoplastic disordered overgrowth of normal tissue, NORMAL to the site of occurrence
Choristoma: Benign normal tissue seen in ABNORMAL location
Teratomas
Originate in germ cells
Teratoma cells contain all three germ cell layers:
- Endoderm
- Mesoderm
- Ectoderm
Melanoma vs melanocytic naevus:
Melanoma: Malignancy of melanocytes
Melanocytic naevus: Benign proliferation of melanocytes
Haematological malignancies based on cell of origin
Lymphoma:
- Malignancy of B or T cells, usually in lymph nodes
Myeloma:
- Malignancy of plasma cells
Leukaemia:
- Malignancy of WBC beginning in bone marrow
Metastasis definition:
The spread of tumour to a site discontinuous from the source organ / tissue
Dysplasia and carncinoma in-situ
Dysplasia:
- Neoplastic change confined within basement membrane
- Cytomorphological features of malignancy
Carcinoma in-situ:
- Severe dysplasia
- Cytomorphological features of malignancy but without invasion (basement membrane not penetrated)
- NOT malignant
Hallmarks of cancer
- Avoids immune destruction
- Evades growth suppressors
- Enabling replicative immortality
- Resisting cell death
What is clonality?
Proliferation of genetically unstable cells producing tumour cell variants
How do cells become immortal?
Autocrine growth stimulation:
- Abnormal expression of oncogenes
- Inactivation do tumour suppressor genes
Reduced apoptosis:
- Abnormal expression of gene that inhibits apoptosis
Telomerase:
- Prevents shortening of telomeres
What are tumour suppressor genes and their role?
Genes that inhibit neoplasticism growth:
- E.g TP53 (encodes for p53)
p53:
- Both caretaker (DNA repair) and gatekeeper (stops damaged cells dividing) function
- Missense and nonsense mutations can cause it to lose function
