Bone Tumours

· primary bone tumours are rare after 3rd decade

· metastases to bone are relatively common after 3rd decade

Diagnosis

· pain, swelling, rarely regional adenopathy

· routine x-ray

o location (which bone, diaphysis, metaphysis, epiphysis)

o size

o lytic/lucent vs. scluotic

o involvement (cortex, medulla, soft tissue)

o matrix (radiolucent, radiodense or calcified)

o periosteal reaction

o margin (geographic n. permeative)

o any pathological fracture

o soft tissue swelling

· malignancy is suggested by rapid growth, warmth, tenderness, lack of sharp definition

· staging should include

o bloodwork Including liver enzymes

o CT chest

o bone scan

o bone biopsy

o ––should be referred to specialized centre prior to biopsy

o ––classified into benign, benign aggressive. and malignant

· MRl of affected bone

Benign Active Bone Tumours

1. Ostaold Osteoma

· peak incidence in 2nd and 3rd decades, M:F = 3:1

· small, round radiolucent nidus ( <1 cm) surrounded by dense bone

o tibia and femur most common

· produces severe intermittent pain. mostly at night (diurnal prostaglandin production)

· characteristically relieved by NSAIDs

· not known to metastasize

2. Osteochondroma

· 2nd and 3rd decades, M:F = 1.8:1

· 45% ofall benign bone tumours

· metaphysis of long bone (distal ends of femur /proximal ends of humerus)

o cartilage-capped bony spur on surface of bone ('"mushroom" on x-ray)

o may be multiple (hereditary, autosomal dominant form) - higher risk of malignant change

· generally very slow growing and asymptomatic unless impinging on neurovascular structure

· malignant degeneration occurs in 1-2% (becomes painful or rapidly grows)

3. Enchondroma (Figure 54)

· 2nd and 3rd decades

· 50% occur in the small tubular bones of the hand and foot; others in femur, humerus, ribs

· benign cartilagenous growth, develops in medullary cavity

o single/multiple enlarged rarefied areas in tubular bones

o lytic lesion with sharp margination and central calcification

· malignant degeneration occurs in 1-296 (pain in absence of pathologic fracture is an important clue)

· not known to metastasize

4. Cystic Lesions

· includes unicameral/solitary bone cyst (most common), fibrous cortical defect

· children and young adults

· local pain. pathological fracture (50% presentations) or incldental detection

o lytic translucent area on metaphyseal side of growth plate

o cortex thinned/expanded; well defined lesion

· aspiration cystic fluid: green/yellow colour with high ALP

· treatment of unicameral bone cyst with steroid injections ± bone graft

Treatment

· treatment only necessary if symptomatic

· osteochondroma: resection

· cystic lesions: currettage and bone graft

Benign Aggressive Bona Tumours

Giant Cell Tumours/Aneurysmal Bone Cyst/Osteoblastoma (Figure 55)

· affects patients of skeletal maturity, peak 3rd decade

· found in the distal femur, proximal tibia, distal radius, sacrum, tarsal bones, spinal (osteoblastoma)

· cortex appears thinned, expanded; well-demarcated sclerotic margin; T2 MRI enhances fluid within lesion (hyper-intense signal)

· local tenderness and swelling

· 15% recur within 2 years of surgery

· giant cell tumour occasionally metastasizes (1-2%)

Treatment

· intralesional curettage + bone graft or cement

· wide local excision of expendable bones

Malignant Bone Tumours

1. Osteosarcoma (Figure 56)

· most frequently diagnosed in 2nd decade of life (60%)

· history of Paget's disease radiation

· predilection fur distal femur (45%), proximal tibia (20%) and proximal hwnerus (15%)

o invasive, variable histology; frequent metastases without treatment Oung most common)

· painful. poorly defined swelling. decreased ROM

· Hay shows Codman’s triangle (Figure 53)

o ––characteristic periosteal elevation and spicule formation representing tumour extension into periosteum

o destructive lesion in metaphysis may cross epiphyseal plate

· treatment: complete resection (limb salvage, rarely amputation), neo-adjuvant cbemo

· survival- 70%

2. Chondrosarcoma (Figure 57)

· primary (2/3 cases)

o previous normal bone, patient over 40; expands into cortex to give pain, pathological fracture, flecks of calcification

· secondary (1/3 cases)

o ––malignant degeneration of pre-existing cartilage tumour such as enchondroma or osteochondroma, younger age group and better prognosis than primary chondrosarcoma

· most commonly occurs in pelvis, femur, ribs, scapula, humerus (with metastasis to the hung)

· unresponsive to chemotherapy, treat with aggressive surgical resection+ reconstruction

3. Ewing's Sarcoma

· most occur between 5-20 years old

· florid periosteal reaction in diaphysis of long bone

o moth-eaten appearance with periosteal lamellated pattern (onion-skinning)

· present with mild fever, anemia, leukocytosis and increased ESR/LDH

· metastases frequent without treatment

· treatment - resection, chemotherapy, radiation

· survival- 70%

4. Multiple Myeloma

· most common primary malignant tumour in adults

· 90% occur in people >40 years old

· present with anemia, anorexia, renal failure, nephritis, increased ESR, bone pain (cardinal early symptom), compression fractures, hypercalcemia

· high incidence of infections (e.g. pyelonephritis/pneumonia)

· diagnosis

o CT-guided biopsy of lytic lesions at multiple bony sites

o serum/urine protein electrophoresis

· treatment chemotherapy, radiation, surgery for symptomatic lesions or impending fractures

5. Bone Metastases

· 2/3 from breast or prostate; also consider thyroid, lung, kidney

· usually osteolytic; prostate occasionally osteoblastic

· bone scan for MSK involvement, MRI for spinal involvement may be helpful

· stabilization of impending fractures

o internal fixation, IM rods

o bone cement