Malignant tumours of the bone
19/10/21 22:12
parameters osteosarcoma
definition Highly malignant tumour of the bone, characterised by formation of bony
Predisposition Age: has a bimodal age distribution
1. Three fourth occur in between 10-20 years of age - OCCURS DURING
THE FASTEST GROWTH
2. Secondary develop in elderly due to secondary disease like paget's
Sex: affects more boys than girls
Etiology -
pathogenesis Primary osteosarcomas:
1. Mutations in tumour supressor genes:
a. RB gene - 2/3rd of the patients
b. Li fraumeni syndrome - TP53 mutations have a greater inciden
2. Inactivation of CDKN2A which codes for p16 [a negative regulator o
3. MDM2 and CDK4 - they are overexpressied in many low grade OS
Secondary osteosarcoma:
Association with pre-existing bone disorders. These bone disorders includ
1. Paget's disease
2. Radiation of exposure: following therapeutic radiation for tumour, s
3. Radium watch dial painters - wetted their brush by licking them
4. Chemotherapy: children treated with alkylating agents have an incr
5. Pre-existing benign bone lesions: fibrous dysplasia, osteomyelitis a
morphology Based on the morphology it can be classified as: [DANPH]
1. Anatomic site of origin:
a. Conventional [classical, medullary, intramedullary, textbook]
b. Intracortical
c. Surface os
i. Parosteal: arise on the surface of the cortex
ii. Periosteal: arose on the surface of the periosteum
2. Degree of differentiation: similar to proliferative epithelial without
squamous cell carcinoma
a. Well differentiated
b. Moderately differentiated
c. Poorly differentiated
3. Number of tumours:
a. Solitary
19/10/21 22:12
parameters osteosarcoma
definition Highly malignant tumour of the bone, characterised by formation of bony
Predisposition Age: has a bimodal age distribution
1. Three fourth occur in between 10-20 years of age - OCCURS DURING
THE FASTEST GROWTH
2. Secondary develop in elderly due to secondary disease like paget's
Sex: affects more boys than girls
Etiology -
pathogenesis Primary osteosarcomas:
1. Mutations in tumour supressor genes:
a. RB gene - 2/3rd of the patients
b. Li fraumeni syndrome - TP53 mutations have a greater inciden
2. Inactivation of CDKN2A which codes for p16 [a negative regulator o
3. MDM2 and CDK4 - they are overexpressied in many low grade OS
Secondary osteosarcoma:
Association with pre-existing bone disorders. These bone disorders includ
1. Paget's disease
2. Radiation of exposure: following therapeutic radiation for tumour, s
3. Radium watch dial painters - wetted their brush by licking them
4. Chemotherapy: children treated with alkylating agents have an incr
5. Pre-existing benign bone lesions: fibrous dysplasia, osteomyelitis a
morphology Based on the morphology it can be classified as: [DANPH]
1. Anatomic site of origin:
a. Conventional [classical, medullary, intramedullary, textbook]
b. Intracortical
c. Surface os
i. Parosteal: arise on the surface of the cortex
ii. Periosteal: arose on the surface of the periosteum
2. Degree of differentiation: similar to proliferative epithelial without
squamous cell carcinoma
a. Well differentiated
b. Moderately differentiated
c. Poorly differentiated
3. Number of tumours:
a. Solitary
