Osteosarcoma & Ewing Sarcoma (DRAFT) Flashcards
What are the 4 most common primary malignancies of bone from most to least common?
MOCE:
- multiple myeloma
- osteosarcoma
- chondosarcoma
- Ewing sarcoma
Which of the 4 most common primary malignancies of bone occur in older populations?
Multiple Myeloma & Chondrosarcoma
(MOCE)
Which of the 4 most common primary malignancies of bone occur in younger populations?
Osteosarcoma & Ewing sarcoma
(MOCE)
(Primary/Secondary) malignancies of bone account for 70% of all bone malignancy
Secondary
What population is primarily affected by osteosarcomas?
Bimodal:
- <20 years (75%; primary)
- Older adults with predisposing conditions (secondary)
What is the most common primary bone tumor in children?
Primary osteosarcoma
What conditions can predispose older adults to developing a secondary osteosarcoma?
- Pagets
- Hx of radiation therapy (20 yr latency period)
- Bone infarct
What is the preferential location of osteosarcoma?
- Metaphysical region of long bones -> extends into diaphysis
- knee (50%)
- secondary osteosarcoma common in flat bones
What is the etiology of osteosarcoma?
Mutations in tumor suppressor genes & oncogenes
Name 5 genes that could be mutated to cause osteosarcoma
- RB
- TP53
- INK4a
- MDM2
- CDK4
What type of gene is RB?
Tumor suppressor gene
What is the function of RB?
Negative regulator of cell cycle (slows/stops)
What type of gene is TP53?
Tumor suppressor gene
What is the function of TP53?
Encodes P53
What is the function of P53?
Promote DNA repair and apoptosis of damaged cells
What is the function of the INK4a gene?
Encodes p16 and p14 (tumor suppressors)
What is the function of MDM2 and CDK4?
Inhibit p53 and RB function
(Allows damaged cells to live)
What genes are overexpressed in many osteosarcomas?
MDM2 and CDK4
What are the gross characteristics of an osteosarcoma?
- progressively enlarging soft tissue mass beyond bone
- mixed blastic (ossification) & lytic (cortex destruction) mass
- irregular margins
- may lift/penetrate periosteum (aggressive Rxn)
- hemorrhagic marrow
- invasive (may metastasize)