Osteosarcoma is the primary malignant tumor, malignant mesenchymal cells produce osteoid and/ or immature bone.
It is the most common primary malignant bone tumor
Classification of Osteosarcoma
Etiology
Previous Radiation Therapy
Paget Disease of Bone
Germ cell abnormality ( Li Fraumeni Syndrome p53 mutation)
Werner Syndrome
Rothmond Thomson Syndrome
Bloom Syndrome
Hereditary Retinoblastoma
Age distribution: Bimodal distribution
Mostly in 2nd decade and after 5th decade
Common Site of occurrence of Osteosarcoma
Metaphysis of long bone
Example: Distal femur and proximal tibia
Clinical Features
Swelling
Persistent Pain
The motion of the adjacent joint is not impaired until the muscle acting on the joint becomes involved by infiltrating tumors
Radiological Investigations
High-grade Osteogenic Sarcomas: Osteoblastic Lesion
The mixture of Radioopacities: Due to Osteogenesis
The mixture of Radiolucency: Due to destructive changes
It represents aggressive lesions: Permeative growth pattern, indistinct margins, and cortex erosion.
Fine lines of increased density, representing newly formed spicules of bones, radiate laterally from the right angle to the surface of the shaft: Sunray Appearances (Sun Brust)
Elevated Periosteum, triangular reactive periosteal ossification: Produces triangular opacity at Upper and Lower angles (Codmann’s triangle)
MRI:
To see the involvement of epiphysis and penetration of physeal cartilages
Chest CT should be done as lung is the most common site for metastasis
Laboratory Investigation
ALP and LDH carry prognostic significance
Bone Scan for skip Lesions: Second most common site for Metastasis
Pathology
Consistency: Stony hard to soft and gritty
Color:
- Fibrous: White
- Osseous: Yellowish white
- Cartilaginous: Bluish White
Vascular channels and hemorrhages are seen
Microscopic Examinations
Spiral, Epitheloid, Oval, round, polygonal, multinucleated, or pleomorphic cells
Hyperchromatic and shows nuclear anaplasia
Characteristics: Osteoid ( dense, pink, and amorphous materials)
Osteoid matrix: Filigree-Like
Dahlin Classification of Osteosarcoma
Depending upon the predominant tissue type
- Osteoblastic
- Chondroblastic
- Fibroblastic
Treatment Options
Osteosarcoma : Radioresistant
High grade: Surgical Excision + Chemotherapy
See also: Musculoskeletal Malignancy: Management
Surgical Option:
Radiotherapy:
Selected Cases
With close surgical margins
Examples: Pelvis, thorax, head, and neck
Palliative radiotherapy
Parosteal Osteogenic Sarcoma
It arises from the outer layer of bone (Periosteum)
Low grade: Favorable prognosis
Arises are directly adjacent to but distinct from the external surface of the bone.
Most common site: Posterior aspect of the distal femur > Proximal humerus.
Chemotherapy is not needed in this variant.
Surgery is the treatment of choice.
Periosteal Osteogenic Sarcoma
It arises from the inner germination layer of the periosteum.
It arises from the diaphyseal cortex or periosteum.
It contains remarkable cartilaginous components so difficult to distinguish from chondrosarcoma.
The most common site is Tibial Shaft.
Chemotherapy is needed for treatment.
Secondary Osteogenic Sarcoma
Background of previous Paget’s disease, bone infarction, fibrous dysplasia, or radiation
Uncommon in young patients
Do not respond well to adjuvant therapy.
