Bone Tumours

Overview

Classification of bone tumors

Classification	Tumors
Primary Bone forming (benign)	Osteoma, osteoid osteoma, osteoblastoma
Primary Bone forming (malignant)	Osteogenic sarcoma (osteosarcoma)
Primary Cartilaginous (benign)	Osteochondroma, chondroma, chondroblastoma (enchondroma)
Primary Cartilaginous (malignant)	Chondrosarcoma
Primary Fibrous	Non-ossifying fibroma, ossifying fibroma, fibrous dysplasia, desmoplastic fibroma, malignant fibrous histiocytoma
Primary Vascular	Hemangioendothelioma, hemangiopericytoma, angiosarcoma
Others	Giant cell tumor (osteoclastoma), bone cyst, ewing sarcoma, adamantinoma, chordoma

Most common bone tumors by age group

Age group	Common tumors
Paediatric	Ewing sarcoma, osteogenic sarcoma (osteosarcoma)
Adult	Metastasis to bone, multiple myeloma, lymphoma, sarcoma of soft tissue

Bone tumors by location

Location	Tumors
Skull	Eosinophilic granuloma, metastasis, myeloma
Mandible	Adamantinoma, dentogenic cyst
Humerus	All tumors, simple bone cysts
Ribs	Metastases, enchondroma, chondrosarcoma, ewing’s sarcoma
Spine	Metastases, myeloma, osteoblastoma, chordoma, hemangioma, aneurysmal bone cyst, chordoma
Pelvis	Osteosarcoma, chondrosarcoma, simple bone cyst, lymphoma, ewing’s sarcoma, chordoma
Distal radius	Giant cell tumor, eosinophilic granuloma
Hands	Enchondroma
Proximal femur	Simple bone cyst, fibrous dysplasia, enchondroma, ewing sarcoma, eosinophilic granuloma
Around the knee	All tumors, osteosarcoma, ewing’s sarcoma
Tibia shaft	Non-ossifying fibroma, fibrous dysplasia, adamantinoma, osteoid osteoma
Calcaneus	Simple bone cyst, ewing’s sarcoma, osteoblastoma, chondroblastoma

• Warning signs for bone tumors
  • Unremitting bone or jont pain (especially pain that wakes the patient from sleep)
  • Rapid progression of bone or joint pain, growth or swelling
  • Constitutional symptoms: fever, chills, shortness of breath, night sweats and weight loss
  • Multiple areas of involvement
• Approach to imaging
  • Which bone is affected?
    • Different locations have different tumors
  • Is the patient skeletally mature or immature?
    • Has the epiphysis and metaphysis fused?
  • Where is the lesion located?
    • At the epiphysis, metaphysis or diaphysis?
    • Central or eccentric?
    • Cortical or medullary?
  • What are the margins?
    • Well-defined or poorly defined
  • What is the zone of transition?
    • Geographic zone of transition = well-circumscribed with or without sclerotic border
    • Moth-eaten zone of transition = poorly-defined (difficult to determine where the lesion begins and normal bone ends)
    • Permeative zone of transition = barely perceptible
  • What matrix is present?
    • Ground-glass appearance (immature woven bone)
    • Osteoid (bone-like, appears as clouds)
    • Chondroid (cartilage-like, appears as rings and arcs)
  • What is is the periosteal reaction?
    • Onion skin (multi-layered)
    • Codman’s trinagle
    • Hair-on end (spicullated)
    • Sunburst
  • Is there soft tissue involvement?
  • Is the lesion solitary or are there multiple lesions?
    • Multiple tumors occur in metastases and fibrous dysplasia

MSTS (Enneking) Tumor Staging

Enneking tumor staging involves tumor grade, local spread (intra- or extracompartmental) and metastatic spread

Stage	Grade	Site	Metastasis
IA	Low grade	T1 – intracompartmental	M0
IB	Low grade	T2 – extracompartmental	M0
IIA	High grade	T1 – intracompartmental	M0
IIB	High grade	T2 – extracompartmental	M0
III	Metastatic	T1 or T2 intracompartmental or extracompartmental	M1

Osteogenic Sarcoma (Osteosarcoma)

Osteosarcoma is the most common primary bone tumour in individuals < 30 years. It most commonly occurs at the metaphysis of the distal femur and proximal radius. Chemotherapy plays a crucial role since micrometastatic disease is present in about 80% of patients at the time of presentation. There are various subtypes (osteoblastic or classic type is the most common). Osteosarcoma secondary to radiation or Paget’s disease tends to be more aggressive.

Commonly seen in older children and young adults aged 10-20 years (75%), with a second peak in older adults aged 60-79 years (secondary to radiation or Paget’s disease). Incidence is low worldwide.

• Risk factors for osteosarcoma
  • Paget’s disease
  • Radiation
  • Bone infarction
  • Li-fraumeni syndrome
  • Retinolastoma
• Patient history
  • Low-grade pain of insidious onset
  • May report a history of trauma which is not proportional to the duration of pain
• Signs and symptoms
  • Pain
    • Dull and progressive
  • Mass may be present
  • Pathological fractures in advanced disease
• Investigations
  • X-ray of the affected area: best initial step. Also used for staging
    • “Sunburst” pattern (looks like cotton balls due to periosteal reaction)
    • Mass often extends beyond the periosteal margins
    • Codman triangle (new born formation in response to periosteal lifting)
  • MRI: for staging. Delineates medullary and extra-osseus extension of the tumor
  • CT-scan of chest: rule out lung metastases
  • Bone scan: evaluate for bone metastases
  • Biopsy: definitive histological diagnosis
  • Labs (ALP, LDH and ESR): Elevated
• Treatment
  • Neoadjuvant chemotherapy
  • Wide excision of the tumor with limb salvage if possible
  • Amputation if the limb cannot be salvaged (due to late presentation) or their is lack of adjuvant treatment options
  • Adjuvant chemotherapy

Ewing’s Sarcoma

Ewing’s sarcoma is the second most common primary bone tumor in patients less than 30 years old. It commonly occurs along the diaphysis of the long bones. Ewing’s sarcoma is a small, round, blue cell tumor and they nearly always involve a t(11;22) translocation. Prognosis is poor for metastatic disease (25% survival with treatment).

Generally a rare cancer. Occurs in young children aged 5 to 15 years. Affects malses more than females.

• Patient history
  • Low-grade pain of insidious onset
  • No history of trauma to the affected area
• Signs and symptoms
  • Persistent, low-grade pain over the site
  • Mass may be present
  • General signs and symptoms of malignancy: fatigue, weight loss
• Investigations
  • X-ray of the affected area:
    • Lytic destruction of the bone
    • “onion-skin” periosteal reaction
    • Lesion extends into the surrounding soft-tissue
  • Bone scan: evaluate for metastases to other bones
  • Bone marrow biopsy: to look for metastases to bone marrow
• Treatment
  • Wide excision
  • Adjuvant chemotherapy
  • Radiation (may or may not be used)

Osteosarcoma vs Ewing’s Sarcoma

	Osteosarcoma	Ewing’s Sarcoma
Age group	Most common in < 30 years. Second peak at age 60 – 79 years	Second most common tumor in < 30 years
Location	Metaphysis of distal femur and proximal tibia	Diaphysis of femur and tibia (long bones)
Bony lesion	Blastic	Lytic
Periosteal reaction	“Suburst” extensive periosteal reaction with a Codman triangle	“Onion-skin” extensive priosteal raeaction
Soft tissue involvement	May or may violate the cortex and extend into soft tissue	Violates the cortext and often has significant soft tissue invovlemtn
Histopathology	High-grade anaplastic cells with surrounding bone islands	Numerous small round blue cells with prominent nuclei and scant cytoplasm
Treatment	Neoadjuvant chemotherapy, wide excision and adjuvant chemotherapy	Wide surgical excision and adjuvant chemotherapy

Bone Metastases

Bone metastases are the most common bone tumours in patients older than 40 years. Metastases can be either blastic or lytic. Common tissue sources include the breast, lung, thyroid, kidney and prostate. Lung and prostate cancer are the most common sources of metastases in men, while lung and breast cancer are the most common sources in women. Prognosis with bone metastases is poor.

Tissue sources of bone metastasis

Tissue source	Description
Breast	Occur as mixed lytic and blastic lesion
Lung	Common in both men and women. More likely to occur distal to the knee and elbow and are lytic lesions
Thyroid	Occur as lytic lesions. Very vascular and may require pre-op embolization before surgery
Kidney	Lytic lesions that occur distal to the knee and elbow. Very vascular and may require pre-op embolization.
Prostate	Occur as blastic lesion

• Patient history
  • Pathological fracture (fracture that happens with routine activity or insignificant trauma)
  • History or signs and symptoms of malignancy
• Investigations
  • X-ray over the affected area: one of the best regions to look for blastic region is the pelvis/vertebrae
    • Blastic lesions (including ivory vertebrae)
    • Lytic lesions
  • CT-scan of the chest/abdomen/pelvis: to look for primary cancer or other metastases
  • Bone scan: to evaluate for metastases to otehr bones
  • Complete blood count with differential
  • Electrolytes, renal function test
  • Liver function test
  • C-reactive protein and erythrocyte sedimentation rate
  • Lactate dehydrogenase
  • Alkaline phophatase
  • Prostate-specific antigen
  • Serum protein electrophoresis (SPEP) and Urine protein electrophoresis (UPEP): to evaluate for multiple myeloma
• Treatment
  • Treat the underlying tumor
  • Fixation of pathological fractures
  • Prophylactic fixation in some patients (use Mirel’s criteria which assesses the risk of pathological fracture, a score ≥ 9 suggests a benefit of prophylactic fixation)

Chondrosarcoma

Chondrosarcoma is the third most common primary bone tumour. It is a primary chondroid tumour. It commonly occurs in the pelvis, shoulders and ribs. Chondrosarcoma has several primary subtypes but can also occur due to malignant transformation of osteochondroma or enchondroma.

• Investigations
  • X-ray of the affected region
    • Popcorn calcifications
• Treatment
  • Wide or radical excision (these tumors are not chemo- or radiosensitive)

Giant Cell Tumours

Giant cell tumours are aggressive but non-malignant tumours of the bone. They commonly occur in long bones (distal radius and proximal humerus). Biopsy shows multinucleated giant cells in a mononuclear stroma. Even though this tumour is benign, it causes significant destruction to bone. The prognosis is worse if there is metastasis.

Rare. Occurs mainly in women aged 20-40 years.

• Investigations
  • X-ray of affected region
    • Eccentric
    • Epi-metaphyseal lytic lesions that erode into subchondral bone
  • Chest X-ray: rule out lung metastases
  • Biopsy
• Treatment
  • Operative curettage
  • Wide excision (if there are pathological fractures)
  • Adjuvant chemothreapy

Osteofibrous dysplasia

Osteofibrous dysplasia is a benign bony tumor of childhood. It is though to be a precursor to adamantinoma. Commonly affects the anterior cortex of the diaphysis of the tibia. Treatment involves correcting the deformity caused by growth of the tumor

Occurs in young males.

• Investigations
  • X-ray of the affected region
    • Soap-bubble appearance

Adamantinoma

Adamantinoma are aggressive, low-grade tumors that can metastasizeb. They represent a progression from osteofibrous dysplasia. They also affect the anterior cortex of the tibia diaphysis.

• Signs and symptoms
  • Palpable anterior tibial mass
• Investigations
  • X-ray of the affected region
    • Soap-bubble appearance
  • Chest X-ray: rule out lung metastasis
• Treatment
  • Wide excision

Chordoma

Chordomas are rare, slow-growing malignant tumours of the bones of the skull and spine. They arise from remnant notochord cells. They most commonly affect the sacrum and clivus on the base of the skull. They are the most common primary malignant sacral tumour (35-50% occur in the sacrum). Histology shows epithelioid cells arranged in cords with physaliphorous (physaliferous cells and a vacuolated “bubble” appearance of the cytoplasm.

Common in middle-aged to older men.

• Signs and symptoms
  • Bowel and bladder dysfunction (due to compression of the sacral nerve roots)
• Investigations
  • MRI: best initial test
    • Destructive bony lesion with large soft tissue mass
• Treatment
  • Surgical excision with muscle flaps and mesh for reconstruciton
  • Urinary diversion and colostomy (if there is loss of bowel and bladder function

Primary Fibrous Bone Malignancy

There are two main fibrous tumors of bone:

Primary fibrous malignancy

Tumor	Description
Desmoplastic fibroma	Bony counterpart of desmoid tumor (aggressive fibromatosis) in soft tissue. Classified as non-malignant because the do not metastasize but are locally aggressive
Malignant fibrous histiocytoma (MFH) of bone	Bony counterpart of MFH of soft tissue. Occurs in the metaphyses of long bones and appears similar to osteosarcoma. Treated with wide surgical excision

Primary Vascular Bone Malignancy

Primary vascular malignancies arise from the vascular components of bone. There are rare and have three types:

Tumor	Description
Hemangioendothelioma	Arises from teh vascular endothelium in long bones. Treated by bone curettage (low-grade lesion) and wide excision (high-grade lesion)
Solitary fibrous tumor	Previously known as hemangiopericytoma
Angiosarcoma of bone	Typically occurs in elderly men. Treated by wide excision or radiation (if non-resectable)

Osteoid Osteoma

• Epidemiology
  • Cause of painful scoliosis in adolescents
  • M:F 3:1
  • Age 5-25 years
  • Most common in the lower extremity (>50%)
• Pathoanatomy
  • Consists of
    • Nidus- a central nodule of woven bone and osteoid with osteoblastic rimming
    • Reactive zone- area of thickened bone and fibrovascular tissue

Soft Tissue Sarcoma

Discussed under general surgery

Multiple Myeloma

Discussed in hematology