Orthopaedic Oncology: Bone Tumors

• Orthopaedic oncology focuses on bone tumors

Approach to Bone Tumors

• Periosteal reaction occurs when the periosteum reacts to an insult or stimulus
• Periosteal insult can lead to new bone formation
• This reaction prevents the spread of underlying pathology
• Thick/solid periosteal reactions indicate slow-growing or indolent lesions
• Thin/lamellated periosteal reactions suggest rapidly growing or aggressive lesions

X-ray Features and Tumor Types

• Onion peel appearance is associated with Ewing's sarcoma
• Sunburst/sunray appearance is linked to osteosarcoma
• Codman's triangle is noted in osteosarcoma cases
• Solid/thick periosteal reactions are observed in osteomyelitis

Sites of Bone Tumors

• Around the knee (distal femur/proximal tibia) is the most common site overall
• Proximal humerus is often affected by simple bone cysts
• Small bones of hands and feet may be affected by enchondroma
• Spine is a site for hemangioma, osteoblastoma, and metastasis

Classification by Location in Bone

• Epiphysis is associated with chondroblastoma (growth plate visible in children) and giant cell tumor (no growth plate in adults)
• Diaphysis is linked to Ewing's sarcoma, osteoid osteoma, adamantinoma (soap bubble), and fibrous dysplasia
• Metaphysis is connected to osteosarcoma, osteochondroma, aneurysmal bone cyst, unicameral bone cyst, and non-ossifying fibroma

Age-Based Classification of Bone Tumors

• Ewing's sarcoma is typical in the 5 to 25 years, predominantly in the second decade
• Primary osteosarcoma occurs in those 10 to 20 years old, commonly as a malignant bone tumor in children
• Giant cell tumors are seen in individuals between 20 to 40 years old, after skeletal maturity
• Secondary osteosarcoma is found in patients 40 to 60 years old, often linked to Paget's disease, radiation, or teriparatide use
• Chondrosarcoma is noted in individuals 40 to 60 years old
• Metastasis, multiple myeloma, adamantinoma, and chondroma are more common in those over 60

Pulsatile Bone Tumors

• Vascular tumors can be pulsatile, indicated by a bruit upon auscultation
• Osteosarcoma is the most pulsatile type of bone tumor
• Aneurysmal bone cysts can also present as pulsatile tumors
• Giant cell tumors and metastasis from kidney or thyroid are additional considerations

Metastasis

• The most common type is malignant bone tumor
• Breast cancer is the most common source of metastasis
• The lumbar spine is a more frequent location of metastasis than the thoracic vertebrae

Characteristics of Secondary Tumors

• Lung cancer is the most common location for secondary tumors from primary bone tumors
• Bone-to-bone metastasis can involve Ewing's sarcoma or osteosarcoma
• Prostate cancer often shows purely blastic characteristics
• Kidney and thyroid cancers, and medulloblastoma are associated with purely lytic lesions
• Breast cancer may present with lytic or blastic characteristics

Miscellaneous Bone Tumors

• Multiple myeloma is the most common primary malignant bone tumor
• Osteosarcoma is more common than chondrosarcoma as a primary non-hematological malignant bone tumor
• Osteochondroma/exostosis is the most common benign bone tumor
• Osteoid osteoma represents the most common true benign bone tumor

Fibrous Dysplasia

• It is a developmental anomaly where bone tissue is replaced by fibrous tissue
• Femur is the most commonly affected
• X-ray findings include a ground glass appearance and a dense rim (rind sign) around fibrotic tissue
• Can lead to shepherd's crook deformity

Bone Cysts

• Biopsy is the best investigation method

Simple Bone Cyst (SBC)

• SBCs are unilocular with symmetrical expansion
• Common centrally in the metaphysis in individuals 10-20 years old
• Proximal humerus is a common site
• The fluid that it contains is clear/straw colored
• Treatment includes aspiration and steroid injections, or curettage with bone graft

Aneurysmal Bone Cyst (ABC)

• ABCs are multi-loculated with asymmetric, expansile ballooning
• Eccentrically located
• Commonly found around the knee, containing blood
• Treatment involves extended curettage using liquid nitrogen, phenol, or bone cement

Radiological Features of Bone Cysts

• Shows well defined borders
• Simple bone cysts can display a metaphyseal lesion
• ABCs have multiloculated lesions in the metaphysis

McCune-Albright Syndrome

• Polyostotic fibrous dysplasia (multicentric)
• Characterized by pigmentation (café au lait spots)
• Precocious puberty

Osteochondroma/Exostosis

• Most common benign bone tumor (distal femur)
• A developmental malformation of the growth plate
• Can be sessile or pedunculated
• Clinical features include asymptomatic growth
• Pain D/t bursitis, nerve compression, or fracture
• Bony pedicle + cartilaginous cap growing
• Malignant transformation to chondrosarcoma
• Heavy calcification is usually evident on X-rays
• Treat with extra periosteal excision

Enchondroma

• The most common bone tumor in small bones of hands & feet
• Location: metaphyseal
• Treat with extended curettage + bone graft

Associated Syndromes

• Maffucci’s syndrome is associated with multiple enchondromas, cavernous hemangiomas, and lymphangiomas; 100% of cases are premalignant
• Ollier’s syndrome has multiple enchondromas; 30% of cases are premalignant
• Most common tumor of the hand: Squamous cell carcinoma

Chondroblastoma

• Also known as Codman's tumor
• An epiphyseal lesion
• Most common in children (10-25 years, before skeletal maturity)
• X-ray shows punctate/stippled calcification
• Treat with excision and curettage with autologous bone graft

Osteoid Osteoma

• The most common true benign tumor
• Occurs in children and adolescents
• Located in the diaphysis, eccentric/cortical lesion in the femur
• Characterized by a central nidus that produces prostaglandins, leading to night pain relieved by aspirin
• There is often swelling in the thigh or leg
• Treat with NSAIDs for pain relief, radiofrequency ablation, or excision curettage
• MR guided focused ultrasound destruction

Giant Cell Tumor/Osteoclastoma

• Locally aggressive and located epiphysio-metaphyseal
• More common in females
• Occurs in adults (20-40 years, after skeletal maturity)
• Characterized by egg shell crackling
• Biopsy reveals multinucleated osteoclast-like giant cells surrounded by mononuclear stromal cells

Giant cell tumor sites

• Distal end of the femur
• Proximal end of the tibia
• Distal end of the radius

Hemangioma

• Benign, asymptomatic vascular bone tumor
• Occurs in elderly population
• Commonly found in the spine, skull, or pelvis Radiological features include:
• X-ray: vertical striations that resemble jail bars
• CT scan: polka dot sign

Osteosarcoma

• Frequent bone tumor in children
• Bimodal presentation peaks in the 2nd decade (1° osteosarcoma) and in older populations (2° osteosarcoma)
• Primary cases is more common than secondary cases
• Located in the metaphysis, commonly in the distal femur
• Most radio-resistant tumor
• Can be induced by radiation
• X-ray shows sun ray/sunburst appearance
• Elevated periosteum
• Codman’s triangle

Osteosarcoma Treatment

• Involves neoadjuvant chemotherapy before surgery
• Surgery typically involves limb ablation
• Adjuvant chemotherapy follows post surgery.
• Regimen used is the T10 protocol:
  • Actinomycin
  • Cyclophosphamide
  • Bleomycin
  • High dose methotrexate
  • Doxorubicin
  • Vincristine

Ewing’s Sarcoma

• Common tumor in the 1st decade of life (5-20 yrs)
• More common in males than females
• Located in the diaphysis of femur (mid thigh swelling).
• High grade sarcoma
• Poor prognostic factors
  • Metastasis
  • Males
  • Fever, anemia
  • ↑ESR
  • Age more than 12 years

Clinical features

• Presents with infection and mid leg swelling
• Look for signs of inflammation either clinical or lab related
• Incidental trauma history
• Small, round blue cells with pseudo-rosettes
• PAS +ve & Diastase digestible
• MIC-2 (CD99) on immunohistochemistry: Specific marker
• Karyotyping: Translocation t(11;22)
• X-ray displays onion peel/lamellated appearance
• Treat with Chemotherapy + Limb Salvage, Resection and adjuvant radiation
• Radiosensitive, but do not undergo radiotherapy due to a higher chance of malignancy and recurrence