Chondrosarcoma

Definition 

 

Malignant cartilage producing tumour 

 

Epidemiology

 

20% of primary bone tumours

 

3rd most common

- 1 in 500 000

 

Relatively non-aggressive / usually Grade I

 

Average age 40

 

Male > Females

 

Two Distinct Types

 

1.  Primary Chondrosarcoma

 

Arises de novo

 

2.  Secondary Chondrosarcoma (1/4)

 

Chondrosarcoma variant

- arises in existing cartilage lesion

- age > 40

- most common in osteochondromas / enchondromas

- also FD / UBC / Paget's / Radiation

 

A.  Secondary chondrosarcoma in Osteochondroma

 

< 1% chance per lesion 

 

Malignant features

- growth after skeletal maturity

- pain

- calcification in cartilage cap

- disappearance of previous calcification

- cartilage cap > 1-3 cm

- hot on bone scan

- erasure of smooth outline

 

B.  Secondary chondrosarcoma in Enchondroma 

 

Malignant features

- scalloping (endosteal erosion)

- periosteal reaction

- fluffy calcification

- size > 6-10 cm rarely benign

- malignant rare < 20 years

- solitary < Ollier's / Maffucci's

 

C.  Grade 1/2

 

Intra-osseous cartilage forming tumour with worrisome clinical or radiological changes

- i.e. pain at site of previous painless enchondroma

- expansion / large size / endosteal scalloping

 

Problem

- is a diagnostic and management dilemma for radiologists / pathologists / orthopaedic surgeons

 

Management

- biopsy

- can miss malignant areas / sampling errors

- probably best to excise in entirety via curettage to examine all tissue

- covert to resection if frankly malignant

 

Variants

 

1.  Dedifferentiated 

 

Area of low grade with juxtaposed area of anaplastic sarcomatous component

- very aggressive tumour

- prognosis is poor

- few survivors two years after diagnosis

 

2.  Clear Cell 

 

Epiphyseal lesion in young males 

- end of major long bones

- proximal humerus and distal femur

 

Likely malignant chondroblastoma

- destructive low grade

- slow growing

- metastasis very rare

 

Histology

- many cells with abundant clear vacuoles lying between abundant heavily calcified chondroid material

- DDx renal cell ca / clear cell sarcoma / adenoca

 

Treatment

- wide excision

 

The benign appearance and lack of calcification is often misleading

 

3.  Mesenchymal

 

Rare

- young patient

- often extra-skeletal, ribs and jaw

- ill defined osteolytic lesion

- high metastatic potential

 

10 year survival 30%

 

Characteristic biphasic pattern 

- areas of cartilage or chondroid matrix 

- interspersed with areas of small spindle cells similar to Ewing's in a hemangiopericytoma pattern

 

Treatment

- surgery + chemotherapy

 

Location

 

1. Central

 

Within diaphysis of long bone

 

Lytic lesion with punctate or spotty calcification

- can look like bone island

- 3/4 calcification present on plain film

 

Endosteal scalloping is hallmark of chondrosarcoma

- periosteal reaction often minimal

- soft tissue expansion

- in metaphysis may only see subtle periosteal reaction

- expansion with cortical thickening characteristic (20%)

 

Chondrosarcoma Proximal Femur Xray0001Chondrosarcoma Proximal Femur Xray0002

 

2. Peripheral / Juxtacortical

 

Rare

 

Faintly visible sparse calcification in soft tissues

- often behind knee

- radiating spicules at right angles to cortex

- > 2.5cm (OS <1.5cm)

 

Usually no medullary involvement

- cortex rarely affected

- Codman's triangle occasionally

 

3. Soft Tissue

 

Chondrosarcoma Soft Tissue

 

Rare

Treat as soft tissue sarcoma

 

Clinical

 

Pain (80%)

- pain in benign cartilage tumour must be assumed to be malignant

 

Mass

Referred pain

Pathological fracture

Incidental finding

 

Site

 

Pelvis most common

Shoulder / Femur

 

X-ray

 

Worrisome features

- central

- large > 5cm 

- cortical / endosteal scalloping

- cortical break through

- soft tissue mass

- periosteal reaction

 

Pathology

 

Gross

 

Pearly white

- cauliflower-like mass

- surrounded by pseudocapsule

 

Histology

 

Lobules of cartilage

 

Matrix may have

- calcium / necrosis / myxoid degeneration

 

Features that suggest malignancy

- pleomorphism

- hypercellularity

- mitotic figures

- double nuclei in single lacunae

- multinucleated giant cells

 

Can be a great diagnostic challenge for MSK pathologist

- DDx between benign active and low grade (grade 1/2)

- especially difficult between enchondroma and low grade central CS

 

Grading

 

Borderline / Grade 1/2

 

Low-Grade / Grade 1

 

Mild cell atypia and mild hypercellularity

- frequent calcificaiton

- mitoses absent / necrosis rare

- occasional bi / trinucleate cell

 

Medium-Grade / Grade 2

 

More cellular

- 1-2 mitoses / high power field

- less calcification

 

High-Grade / Grade 3

 

Marked atypia & mitotic figures

- densely cellular

- many double nuclei

- no calcification

- obviously anaplastic

- must have chondroid

 

Management

 

Principles

 

Treatment is wide resection

 

Highly resistant to chemotherapy & radiotherapy

- rate of DNA synthesis slow

 

Radiotherapy

- only used if inoperable

- high grade lesions with incomplete margins

 

Exceptions

- mesenchymal -> chemo & radiotherapy

- dedifferentiated -> chemotherapy

 

Surgery

 

Hemipelvectomy Chondrosarcoma

 

Prognosis

 

1.  Grade

 

Low / moderate Grade - 90% 5 year survival

 

High Grade - <10% 5 year survival

 

2.  Site

 

Peripheral - 80% 10 year survival

 

Central - 30% 10 year survival

 

Metastasis

 

Incidence 15%

- 40% preceded by local recurrence

- local recurrence 6x risk for metastasis

 

Grade II:   15 - 40% risk metastasis

Grade III:  75% risk metastasis