bone neoplasms

Question 1

bone tumours can be grouped into : primary vs metastatic tumours.
which is the most common malignant bone tumour?

Answer 1

Carcinoma

Question 2

Among the primary malignant bone tumours, —– is the most common (35%), followed by —– (25%) and —– sarcoma
(16%*).

Answer 2

osteosarcoma > chondrosarcoma > Ewing

Question 3

Osteosarcoma and Ewing sarcoma mostly affect —–
Chondrosarcoma mostly affect —–

Answer 3

children & young adults
older patients

Question 4

Clinical presentation of primary malignant bone tumour

Answer 4

• Pain, mass & swelling of affected area, fracture and loss of function.
• 20-25% present with metastatic disease [ Lungs (38%) / Bone (31%) / Bone Marrow (11%) ]
• might have constitutional symptoms – fever / anemia / weight loss

Question 5

Common investigations used for bone tumours

Answer 5

1. Xray – IMPT 1st line
2. MRI (or CT)
3. Bone radionuclide bone scan – detect tumour spread to other bones
4. Positron emission tomography (PET) scan – highly sensitive to scan whole body for tumour spread
5. Biopsy (needle / incisional surgical) – gold standard in diagnosing

Question 6

Prognostic factors for primary malignant bone tumours

Answer 6

• Size of tumours (T1 better prognosis than T2. > 8cm or < 8cm).
• Histopathological grading.
• Location of the tumours and margin clearance: Good local control (anatomically resectable limbs) versus poor local control (spine and pelvis).
• Stage: metastatic disease has worse prognosis.
• Response to chemotherapy (good > 90% necrosis) only for osteosarcoma (and Ewing sarcoma).

Question 7

Location of bone tumour -> What tumour

Answer 7

1. Epiphysis : Chondroblastoma
2. Metaphysis (of long bones) : Osteosarcoma
3. Epiphyseal-metaphyseal region : Giant cell tumour

Question 8

Definition of osteosarcoma

Answer 8

A mostly high-grade malignant bone tumor that produces osteoid directly from tumor cells.

Question 9

Risk factors of osteosarcoma

Answer 9

• Male
• Younger (10-25 y/o)
• Older patient often a/w precursor lesion = Paget’s disease

Question 10

X-ray of osteosarcoma

Answer 10

• large, destructive, lytic or blastic mass
• Permeative margins;
• may break through cortex and elevate periosteum;
• sunburst pattern due to new bone formation in soft tissue

Question 11

Histology of osteosarcoma

Answer 11

A lace-like pattern of OSTEOID is produced by eosinophilic matrix entrapping anaplastic tumor cells.

Question 12

Definition of chondrosarcoma

Answer 12

Malignant bone tumour that produces cartilage (but not osteoid).

Question 13

Risk factors of chondrosarcoma

Answer 13

• male
• older (30-60 y/o)
• a/w pre-existing bone tumour (enchondroma or osteochondroma)

Question 14

Characteristics of chondrosarcoma

Answer 14

Often large painful tumors of long bones or ribs that grow rapidly during adolescence and reach 8 cm or larger

NOT chemo sensitive

Question 15

Gross appearance of chondrosarcoma

Answer 15

• Large lobulated tumour with pearly white or light blue, often with focal calcification.
• Myxoid change is more common and suggestive of malignancy.
• Areas of hemorrhagic necrosis may be present.

Question 16

Histology of chondrosarcoma

Answer 16

• Cartilaginous matrix
• Permeation of bone trabeculae
• Soft tissue & marrow invasion

Question 17

Osteochondroma / exostosis

Answer 17

• Most common benign bone tumours arising in the long bones.
• A benign cartilage-capped tumor that is attached to the underlying skeleton by a bony stalk.
• Solitary (85%). Remaining cases multiple hereditary exostoses syndrome (EXT1 and EXT 2 genes).
• Bone extension containing cortex and periosteum covered by a thin cartilaginous cap.
• Rarely undergoes malignant transformation (chondrosarcoma).

Question 18

What is giant cell tumour

Answer 18

• Most common and important of all the giant cell rich neoplasms of the skeleton.
• Benign but locally aggressive neoplasm with high rate of recurrence (up to 30%).
• Usually solitary
• Long tubular bones (usually knee)
• In epiphyseal-metaphyseal region

Question 19

Risk factors of giant cell tumour

Answer 19

• 30-50 y/o
• females
• more common in oriental countries

Question 20

Histology of giant cell tumours

Answer 20

• Abundant giant cells often with numerous nuclei (50 to 100 per cell).
• Stromal cells similar to giant cells.
• No osteoid formation.
• Extremely rare malignant transformation.

Question 21

What’s fibrous dysplasia

Answer 21

• benign tumor reflecting a localized developmental arrest
• All of the components of normal bone are present, but they do not differentiate into mature structures.
• result from a somatic gain-of-function mutation in GNAS1.

GROSS
* tissue is tan-white & gritty
* curvilinear shapes of trabeculae mimic Chinese characters
* bone lacks prominent osteoblastic rimming