Reu 1 - Bone Formation And Bone Tumors

Question 1

Where in the body do we see endochondral ossification?

Answer 1

Mainly in the axial skeletons and the limbs.

Question 2

What is membranous ossification?

Answer 2

The osteoblasts and osteoclasts build the bone directly without cartilage frame.

Question 3

Where does membranous ossification occur?

Answer 3

Bones of the skull.

Question 4

What is the cause of achondroplasia?

Answer 4

An autosomal dominant disease. Caused by fibroblast growth factor receptor (FGFR3) being constitutively on (always on). This inhibits chondrocyte proliferation (they don’t lay down the cartilage models of the bone). It is associated with advanced paternal age, and mutations occur sporadically.

Question 5

What happens when a fetus inherits the dominant achondroplasia gene from both parents that have the disease?

Answer 5

It will die in utero. AA = death. Aa = achondroplasia. aa = normal stature.

Question 6

What is the main cause of bone tumors?

Answer 6

Metastatic from tumors of other organs.

Question 7

What is the most common benign tumor of bone?

Answer 7

Osteochondroma.

Question 8

What is osteochondroma?

Answer 8

The most common benign tumor of bone, occurs in males

Question 9

What is another name for osteoclastoma?

Answer 9

Giant cell tumor of the bone.

Question 10

What is osteoclastoma?

Answer 10

AKA giant cell tumor of the bone, it is a tumor of the osteoclasts. Occurs in adults 20-40.

Question 11

Where are osteoclasts usually located?

Answer 11

On the distal femur or proximal tibius, around the knee.

Question 12

What is the appearance of osteoclastoma on x-ray?

Answer 12

Soap bubble appearance in x-ray. They are radiolucent because the osteoclasts break down bone.

Question 13

What is the most common primary tumor of the bone?

Answer 13

Osteosarcoma.

Question 14

What is Ewing Sarcoma?

Answer 14

Most is caused by 11:22 translocation. Young boys

Question 15

What are the two x-ray findings to know about osteosarcoma?

Answer 15

1. Codman’s triangle: Tumor pushes the periosteum up the surface of the bone, making a triangular density on the bone.
2. Sunburst pattern in the lesion.

Question 16

What is the x-ray finding in Ewing sarcoma?

Answer 16

Onion skin appearance.

Question 17

What age group is vulnerable to Osteosarcoma?

Answer 17

Boys age 10-20.

Question 18

What cancers love to metastasize to the bone?

Answer 18

[Permanently Relocated Tumors Like Bones]

Prostate, Renal cell cancer, Testes/Thyroid, Lung, Breast.

Question 19

What type of lesion do lung cancer metastasis to the bone cause?

Answer 19

Lytic lesions.

Question 20

What type of lesion do prostate cancer metastasis to the bone cause?

Answer 20

Blastic lesion.

Question 21

What type of lesion do breast cancer metastasis to the bone cause?

Answer 21

Lytic or blastic.

Question 22

What are the clinical presentations of bone metastasis?

Answer 22

Bone pain, epidural spinal cord compression, hypercalcemia (lytic bone lesions only).

Question 23

Where does new bone formation takes place in growing long bone?

Answer 23

Epiphyseal plate.

Question 24

What is associated with Ewing sarcoma?

Answer 24

11;22 translocation.

Question 25

What bone tumor is associated with “sunburst” pattern on x-ray?

Answer 25

Osteosarcoma.

Question 26

What bone tumor is associated with “soap-bubble” pattern on x-ray?

Answer 26

Osteoclastoma.

Question 27

What bone tumor is associated with “onion-skin” pattern on x-ray?

Answer 27

Ewing sarcoma.

Question 28

What bone tumor may actually be a hamartoma?

Answer 28

Osteochondroma.

Question 29

What bone tumor is associated with “Codman’s triangle” pattern on x-ray?

Answer 29

Osteosarcoma.

Question 30

What mutation leads to achondroplasia?

Answer 30

FGFR3 (fibroblast growth factor receptor 3).

Question 31

What is endochondral ossification?

Answer 31

When chondrocytes lay down cartilage frame of the bone first, and then osteoblasts and osteoclasts come in later to lay down the bone matrix.