Osteosarcoma (Osteogenic Sarcoma)

Codman’s triangle and Sunray appearance are characteristic radiological findings in osteosarcoma.

When the tumour elevates the periosteum of bone, a gap occurs between periosteum and bone, where the gap is elevated, bone is formed, creating a triangular shape on radiographs.

Ref: Apley’s system of orthopaedics and fractures;8^th/185; Essential orthopedics by Maheshwari 3^rd/219, 222.

A biopsy from the lesion is essential for grading of the tumour but a biopsy from bone marrow is not indicated.

Bone scan, CT chest and MR1 femur are important staging investigations for osteosarcoma.

Ref: Apley’s system of orthopaedics and fractures 8^th/185; Pediatric and Adolescent Osteosarcoma By Norman Jaffe, Øyvind S. Bruland, 2009, Page 209; Final FRCR 2B Long Cases: A Survival Guide By Jessie Aw, John Curtis, 2010, Page 165.

Retinoblastoma: 

• It is the most common primary intraocular malignancy of childhood. 
• The mutation occurs in the retinoblastoma gene (Rb) at chromosome 13q14. This is a tumor suppressor gene. 
• One mutated copy may be inherited in an autosomal dominant fashion (germline mutation). If a second mutation spontaneously occurs in any cell, tumorigenesis is likely. 
• Individuals with a germinal mutation are at risk for the development of tumors other than retinoblastoma (pineal tumors, osteosarcoma, and other soft tissue sarcomas).

Ans. is ‘b’ i.e., Osteomyelitis & c i.e., Paget’s disease of bone

Osteosarcoma (osteogenic sarcoma – OGS)

o Osteosarcoma is primary malignant bone tumor of bone, derived from primitive bone forming mesenchyma and characterized by osteoid formation.

• It is of two types

1. Primary
2. Secondary

o Paget disease

o Radiation

o Fibrous dysplasia

o Enchondromatosis

o Multiple osteochondroma

o Bone infarction

o Chronic osteomyelitis

Ans. is c i.e., c-myc gene implicated in the genesis

o Genetic mutations are fundamental to the development of osteosarcoma. Patients with herediatary retinoblastomas have upto 1000 times greater risk of subsequently developing osteosarcoma, attributed to germline mutation in RB gene. Abnormalities in gene that regulate cycling such as p53, CDK4, p16, INK4A, CYCLINDI and MDM2 have also been implicated in the genesis of nonherediatary osteosarcoma.

Radiological features of osteosarcoma

o X-ray of a patient with osteosarcoma shows following features : –

1)An area of irregular destruction in the metaphysis, sometimes overshadowed by the new bone formation. The

cortex overlying the lesion is eroded. There is new bone formation in the matrix of the tumour.

2)Periosteal reaction : – As the tumor lifts the periosteum, it incites an intense periosteal reaction. The periosteal

reaction in an osteosarcoma is irregular, unlike in osteomyelitis where it is smooth and in layers.

3)Codman’s triangle: – A triangular area of subperiosteal new bone is seen at the tumour host cortex junction at the

ends of the tumor.

4)Sun-ray appearance:- As the periosteum is unable to contain the tumour, the tumour grows into the overlying soft tissues. New bone is laid down along the blood vessels within the tumour growing centrifugally, giving rise to a `sun-ray appearance’ on the X-ray.

B i.e. Sunray appearance

The X Ray findings of osteosarcomas are characterized by:

Variable mixture of radiopacities (due to osteogenesis) & radiolucencies (due to destructive change & replacement by radiolucent osteoid)

–         Sun Burst/ Sun ray appearanceQ

–         Codman’s triangleQ (also found in infection & Ewing’s SA so not specific)

Ans. A: Metaphysis

• Diachysis- common site for ewing’s tumor
• Epiphysis- common site for osteoclastoma

Ans. Peripheral field of differentiation

Ans. Osteosarcoma

Matrix mineralization (calcification) of tumor matrix

• The pattern of mineralization (calcification) on radiograph may be helpful in identifying tumor matrix.
• Dense, homogenous mineralization (calcification) is typical of osteoid matrix, formed by benign and malignant bone-forming lesions.However, osteoid matrix is not always mineralized.
• Calcified rings and arcs, dense punctate calcification, and flocculent calcification (small, loosely aggregated masses) are pattern of mineralization of chondroid matrix, formed by benign and malignant cartilage forming tumors.

Ans:A.)Osteosarcoma

The condition shown in the picture above represents Osteogenic sarcoma.

Osteogenic sarcoma (osteosarcoma)

• It is the most common primary malignant tumor of bone, excluding plasma cell myeloma.
• Osteosarcoma is a bone tumor and can occur in any bone, usually in the extremities of long bones near metaphyseal growth plates. The most common sites are as follows:
  • Femur ,Tibia, Humerus ,Skull and jaw, Pelvis
• Radiograph of the femur in a patient with osteosarcoma shows a typical Codman triangle ( A characteristic often seen in an X-ray is Codman’s triangle(which is basically a subperiosteal lesion formed when the periosteum is raised due to the tumor) and more diffuse, mineralized osteoid within the soft tissues adjacent to the bone.
• Symptoms include pain worse at night, intermittent and of varying intensity .
• It is treated by a combination of surgical excision and chemotherapy.

The arrow marked in the picture above represents the Codman’s triangle.

Codman triangle is the triangular area of new subperiosteal bone that is created when a lesion, often a tumour, raises the periosteum away from the bone. A Codman triangle is not actually a full triangle. Instead it is often a pseudotriangle on radiographic findings with ossification on the original bone and one additional side of the triangle which forms a two sided triangle with one open side. This two sided appearance is generated due to a tumor (or growth) that is growing at a rate which is faster than the periosteum can grow or expand, so instead of dimpling, the periosteum tears away and provides ossification on the second edge of the triangle.

The Codman triangle may be seen with aggressive lesions:

• Osteosarcoma.
• Ewing sarcoma.
• Osteomyelitis.
• Active aneurysmal bone cyst.
• Giant cell tumor.

Ans. c. Periosteal reaction