Malignant Bony Tumours

Overview – Malignant Bony Tumours

Malignant bony tumours are aggressive neoplasms originating from various skeletal cell types. These tumours often present with localised bone pain, swelling, and systemic symptoms, and may result in pathological fractures. Prompt recognition and intervention are vital due to their rapid progression and metastatic potential. This page outlines the major malignant bone tumours relevant to final-year medical students: osteosarcoma, Ewing’s sarcoma, chondrosarcoma, and giant cell tumour of bone.

Osteosarcoma

Definition

A high-grade malignant tumour of osteoblasts, most commonly affecting children and adolescents.

Aetiology

• Malignant proliferation of osteoblasts

Pathogenesis

• Bone-forming tumour with dysplastic osteoblast activity
• Typically arises in metaphyseal regions of long bones

Morphology

• “Chicken-drumstick appearance” (metaphyseal growth)
• Codman’s triangle: periosteal elevation due to subperiosteal tumour spread
• Marrow invasion common

Clinical Features

• Teenagers and children most affected
• Sites: knee and shoulder (distal femur/proximal tibia or humerus)
• Symptoms:
  • Chronic localised bone pain and tenderness
  • Redness and swelling
  • Fever, weight loss
  • No joint involvement
• Complications:
  • Pathological fractures (from mild trauma)
  • Non-healing fractures

Diagnosis

• Avoid biopsy due to risk of seeding
• Use X-ray and bone scan

Management

• Surgical resection + chemotherapy

Prognosis

• <50% curable, but highly chemosensitive

Ewing’s Sarcoma

Definition

A malignant small round-cell tumour, genetically driven.

Aetiology

• Genetic mutation (commonly EWSR1 translocation)

Pathogenesis

• Originates in the medullary cavity of long bones

Clinical Features

• Affects teenagers
• Presents with pain, swelling, and pathological fracture
• Often mimics infection
• Systemic signs: fever, anaemia, leukocytosis

Diagnosis

• X-ray: “moth-eaten” lytic lesion with onion-skin periosteal reaction
• Raised ESR and WBC

Management

• Surgery + chemotherapy + radiotherapy

Prognosis

• Poor prognosis with frequent metastases
• ~80% local, 25% metastatic at diagnosis

Chondrosarcoma

Definition

A malignant tumour of cartilage, more common in adults.

Aetiology

• Primary: unknown
• Secondary: from benign precursor like osteochondroma

Pathogenesis

• Neoplastic proliferation of cartilage-producing cells

Clinical Features

• Adults >40 years
• Often asymptomatic, may present with a pathological fracture

Diagnosis

• X-ray: large exostosis with calcified cartilage cap

Management

• Surgical resection (not responsive to chemotherapy)

Prognosis

• Highly variable: 25–90% 5-year survival depending on tumour grade

Giant Cell Tumour of Bone

Definition

A bone tumour composed of osteoclast-type giant cells, may behave aggressively.

Aetiology

• Unknown

Pathogenesis

• Tumour of osteoclast-monocyte lineage

Clinical Features

• Pain, swelling, and restricted movement (especially near joints)
• Risk of pathological fracture

Management

• Surgical excision, sometimes with radiotherapy
• Bisphosphonates may assist in symptom control

Prognosis

• Often locally aggressive
• Up to 66% may behave malignantly

Summary – Malignant Bony Tumours

Malignant bony tumours—including osteosarcoma, Ewing’s sarcoma, chondrosarcoma, and giant cell tumour—are aggressive neoplasms often affecting young people. Clinical red flags include persistent pain, systemic features, and pathological fractures. Early diagnosis using imaging is crucial, and treatment typically involves surgery with adjuvant therapies depending on tumour type. For more on skeletal malignancies and orthopaedic conditions, see our Musculoskeletal Overview page.