MSK Tumours

Question 1

State the 3 most common primary malignant bone tumours, ranked from most common to least common.

Answer 1

1. osteosarcoma (35%)
2. chondrosarcoma (25%)
3. ewing sarcoma (16%)

Question 2

State the most common malignant bone tumours in paediatrics group, rank them.

Answer 2

1. osteosarcoma
2. ewing sarcoma

Question 3

State the most common malignant bone tumours in adult age group, rank them.

Answer 3

1. metastasis (bone lesion in adult is metastasis until proven otherwise)
2. osteosarcoma and myeloma

Question 4

State the most common malignant bone tumour in elderly

Answer 4

metastasis and chondrosarcoma

Question 5

State the common clinical presentation of primary malignant bone tumour (6)

Answer 5

1. pain
2. mass in affected area
3. swelling of affected area
4. fracture
5. loss of function
6. systemic symptoms (fever, anemia, weight loss, elevated WBC and ESR)

Question 6

____-____ % present with metastatic disease from
- ____ (38%)
- ____ (31%)
- ____ (11%)

State the site that is NOT one of the common primary sites that bone mets come from

Answer 6

20-25 % present with metastatic disease from
- LUNGS (38%)
- BONE (31%)
- BONE MARROW (11%)

LIVER IS NOT ONE OF THE COMMON PRIMARY SITES THAT BONE METASTASIS COMES FROM

Question 7

State the common investigations used for
(1) definitive diagnosis
(2) check for primary or secondary tumours

Answer 7

(1) definitive diagnosis - biopsy (needle or incisional surgical biopsy)

(2) check for primary or secondary tumours - X-ray (first line), MRI/CT scan, bone radionuclide bone scan, positron emission tomography (PET) scan

Question 8

State the prognostic factors for primary malignant bone tumours (5)

Answer 8

1. Size of tumours (T1 is better prognosis than T2)
2. Histopathological grading
3. Tumour staging (TNM)
4. Location of tumours and margin clearance (good local control vs poor local control)
5. Response to chemotherapy

Question 9

State the locations that have worse prognosis when tumour metastasises from them.

Answer 9

liver + bone

Question 10

State the malignant bone tumours that have good response to chemotherapy

Answer 10

1. osteosarcoma
2. ewing sarcoma

Question 11

State the common malignant bone tumours at
1. epiphysis
2. metaphysis
3. diaphysis

Answer 11

1. epiphysis - chondrosarcoma + giant cell tumour
2. metaphysis - osteosarcoma
3. diaphysis - ewing sarcoma

Question 12

Osteosarcoma is a mostly ____-grade ____ bone tumour that produces ____ directly from tumour cells

Answer 12

Osteosarcoma is a mostly HIGH-grade MALIGNANT bone tumour that produces OSTEOID directly from tumour cells

Question 13

State everything you know about osteosarcoma.

Answer 13

OSTEOSARCOMA
- Mostly male
- Younger population
- Older patients often associated with precursor lesion (Paget’s disease)
- X-ray = large, destructive lytic mass with permeative margins
- Sunburst pattern due to new bone formation in soft tissue of metaphysis of long bones
- Usually arises from medullary cavity and extends to cortex
- May break through cortex and elevate periosteum
- Fleshy appearance with necrosis and haemorrhage
- Histology = lace-like pattern of osteoid produced by eosinophillic matirix entrapping anaplastic tumour cells

Question 14

State everything you know about Ewing sarcoma.

Answer 14

• 2nd most common malignant bone tumour in children
• commonly manifests in the second decade (80% in 5-25 year olds)
• radiology = destructive, poorly marginated, permeative, layered periosteal new bone, onion skinning
• histology = sheets or small, round, uniform cells (primitive cells), homer-wright rosettes, positive CD99 immunostain
• UNIQUE TRANSLOCATION t(11,22) (q24;q12)
• differentials = lymphoma, rhabdomyosarcoma, metastatic cancer, neuroblastoma, small cell osteosarcoma

Question 15

Chrondrosarcoma is a ____ bone tumour that produces ____ but not ____

Answer 15

Chrondrosarcoma is a MALIGNANT bone tumour that produces CARTILAGE but not BONES

Question 16

State everything you know about chondrosarcoma

Answer 16

CHONDROSARCOMA
- usually in elderly (30-60 year olds)
- large painful tumours of long bones or ribs that grow rapidly during adolescnce (bones in pelvis, skull and spine)
- may be associated with pre-existing bone tumour
- not chemosensitive, use surgical intervention (do not treat with chemo or radiotherapy)
- macro: large lobulated tumour with white/light blue with focal calcification, myxoid change suggestive of malignancy, haemorrhgae and necrosis
- histology: cartilaginous matrix, permeation of bone trabeculae, soft tissue and marrow invasion

Question 17

State the grading of chondrosarcoma

Answer 17

• grading = based on cellularity and nuclear changes in chondrocytes
• well to poorly differentiated correespond to grades 1-3
• locally aggressive and metastases to lung = higher grade

Question 18

State everything you know about osteochondroma

Answer 18

OSTEOCHONDROMA
- most common benign bone tumour (primary) in the long bones
- can be solitary (85%) or multiple (commonly hereditary - EXT1 and EXT2 genes)
- bone extension containing cortex and periosteum covered by thin cartilaginous cap
- rarely undergoes malignant transformation (chondrosarcoma)

Question 19

State everything you know about chondroma

Answer 19

CHONDROMA
- echondroma = inside bone within medullary cavity
- subperiosteal chondroma = surface of bone
- soft tissue chodnroma = inside soft tissue and no communication with adjacent bone
- mostly solitary (IDH1 and IDH2 genes heterozygous mutations)
- multiple is suggestive of non-hereditary cause (ollier’s disease and maffucci syndrome)

Question 20

State the 3 general rule of thumb for primary bone tumour

Answer 20

benign - malignant
1. no cytological atypia - cytological atypia
2. no permeation of bone trabeculae and marrow - permeation of bone trabeculae and marrow
3. no soft tissue or organ invasion - soft tissue or adjacent organ invasion

Question 21

State the common giant cell rich lesions of bone and joints (4)

State if they are benign or malignant

Answer 21

1. giant cell tumour
2. brown tumour - hyperparathyroidism
3. giant cell reparative granuloma
4. giant cell tumour of joint

all benign (but may be locally recurrent) with very rare malignant cases

Question 22

State everything you know about giant cell tumor of bone

Answer 22

GIANT CELL TUMOUR OF BONE
- most common giant cell rich neoplasm of the skeleton
- benign but locally aggressive with high rate of recurrence (30%)
- more common in females than males
- more common in middle aged (30-50 year olds)
- usually solitary
- affects long tubular bones
- epiphyseal-metaphyseal region
- macro: haemorrhagic brown appearance
- histo: abundant giant cells with numerous nuclei, stromal cells similar to giant cells, no osteoid formation

Question 23

Fibrous dysplasia (FD) is a ____ tumour reflecitng a ____ ____ arrest
- all components of a normal bone are present but they do not ____ into ____ structures
- lesions arise during ____ ____
- can be ____ or ____ (Mazabraud syndrome, McCune-Albright syndrome)
- results from a somatic ____-of-function mutation in ____
- macro: ____ and tan-white
- histo: ____ ____ of woven bone surrounded by ____ ____ proliferation, lacks prominent ____ ____
- bones are hence prone to ____

Answer 23

Fibrous dysplasia (FD) is a BENIGN tumour reflecitng a LOCALISED DEVELOPMENT arrest
- all components of a normal bone are present but they do not DIFFERENTIATE into MATURE structures
- lesions arise during SKELETAL DEVELOPMENT
- can be MONOSTOTIC or POLYOSTOTIC (Mazabraud syndrome, McCune-Albright syndrome)
- results from a somatic GAIN-of-function mutation in GNAS1
- macro: GRITTY and tan-white
- histo: CURVILINEAR TRABECULAE of woven bone surrounded by CELLULAR FIBROBLASTIC proliferation, lacks prominent OSTEOBLASTIC RIMMING
- bones are hence prone to FRACTURE