Approach to Primary Bone Tumour

Steps

 

1. Establish a differential

2. Stage locally and systemically

3. Biopsy

4. Definitive Treatment

 

1. Establish a Differential

 

Lytic Lesion Distal Femur0002

 

Lesion detected on X-ray

 

Questions

- what do you think it is?

- is it benign (latent, active, agressive)?

- is it malignant (primary or secondary)?

 

Enneking's four questions

 

1.  Where is the tumour?

 

Flat bone / long bone

Epiphysis / metaphysis / diaphysis

Medullary canal / cortex

Eccentric in bone

 

2.  What is it doing to the bone?

 

Expansion

Cortical erosion / breakthrough

Fracture

Permeative margins

 

Wide / narrow zone of transition

- narrow / can draw edge with a pen / good sign

- wide / infiltrative / bad sign

 

The best indication of the aggressiveness of a tumour is the transition zone or margin that surrounds the bone

 

3.  What is the bone doing to it?

 

Periosteal reaction

- Codman Triangle / Sunburst / Onion Skinning

 

Reactive rim

- Sclerotic = Slow growing

- Ill defined = Fast growing

 

Margin

1.  Moth eaten / permeative / ill defined / wide zone of transition / cortical or cancellous

2.  Well circumscribed / narrow zone of transition / sclerotic rim

 

4.  Are there any clues to its histological diagnosis?

 

Bone formation / Calcification

Soft tissue component

Radiolucent / ground glass

Matrix Osteoid / Chondroid / Myxoid / Collagen

 

DDx Lucent lesions

 

FOGMACHINES

 

Fibrous dysplasia

Osteoid Osteoma / Osteoblastoma / Osteosarcoma

Giant cell tumour

Metastasis / myeloma

ABC

Enchondroma / Chondroblastoma / Chondrosarcoma

Hemangioma / HPTH

Infection / Intraosseous ganglion or lipoma / Infarct

Non Ossifying Fibroma / Neurofibroma

EG

Simple bone cyst / Synovial Proliferation

 

Patient factors

 

Age

- consider primary bone tumour < age 40 

- consider metastasis > age 40

- consider EG < age 10

 

History

 

Malignant pain

- night time, severe, increasing

Trauma

 

Examination

 

Soft tissue mass = Aggressive lesion

 

Inflammation = Infection / Ewing's 

 

Pathology tests

 

Serum electrophoresis / Urine Bence Jones (Multiple Myeloma)

PSA - prostatic cancer

ESR - non specific (increased in infection / Ewing's / MM / lymphoma / metastasis)

ALP - increased in Osteosarcoma & Paget's

Calcium / PTH - think of hyperparathyroidism

 

Other Tests

 

Mammogram / Thyroid Ultrasound - metastasis

CT Chest / abdomen / pelvis - RCC, lung cancer, bowel cancer

 

Old X-rays

 

Consider observation if lesion unchanged from at least 2 years ago

 

2.  Stage Locally and Systemically

 

Purpose 

- accurately define the extent of the disease

- prior to proceeding with biopsy and definitive treatment

 

Local / Cross sectional imaging

 

CT

 

Best for assessing mineralisation & bony details

- benign bone tumours

- violation of cortex

- matrix mineralisation

- shows areas that plain X-ray visualise poorly i.e. Spine / Pelvis

 

MRI

 

Best for assessing soft tissue component

 

Assess

1.  ST tumours

2.  Cortical breakthrough / T2

3.  Soft tissue extension / T2

4.  Marrow involvement / intramedullary spread

- T1 with fat suppression

5.  Relationship to NV bundle / T2

6.  Joint & Epiphyseal involvement

7.  Infection - rim enhancement on gadolinium

 

Advantage

- guides extent of treatment

- > 5cm margin on MRI / wide excision

 

Disadvantage

- may be oversensitive

- oedema vs tumour

 

Distant

 

Bone scan

 

Determines if lesion polyostotic v monostotic

- this aids with differential diagnosis

- will identify metastasis

 

Bone Scan Metastasis

 

False negative / cold scan

- inactive benign tumours

- myeloma / EG / melanoma

 

CT Chest / Abdo / Pelvis

 

Purpose

- identify primary tumour that may have metastasised to bone

- identify liver and lung metastasis

 

Lung Metastasis CT Chest

 

Classify Lesion

 

Benign - no need for biopsy

Uncertain or malignant - need for biopsy

 

3. Biopsy

 

Aim

 

A.  To determine whether benign or malignant

 

B.  To determine specific cell type

 

C.  To determine grade

 

See Principles of Biopsy

 

4. Definitive Treatment

 

See specific tumour articles