May 30, 2024

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

Classification of Osteosarcoma
Classification of Osteosarcoma


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


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)


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


Consistency: Stony hard to soft and gritty


  • 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:


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.