Pathoma: Bone Tumors

Question 1

Osteomas most commonly arise on the ____________.

Answer 1

facial bones

Question 2

Gardner syndrome raises the risk of what three pathologies?

Answer 2

• Adenocarcinoma in the colon (because Gardner includes a mutation in FAP)
• Fibromatosis in the retroperitoneum: this is a benign proliferation of fibroblasts that can cause symptoms by pressing on adjacent structures
• Osteomas of the facial bones

Question 3

Which is closer to the end of the bone, the epiphysis or the diaphysis?

Answer 3

The epiphysis

Toward the ends of long bones, the diaphysis meets the metaphysis (growth plate) and then the epiphysis caps the end.

Question 4

Describe osteoid osteomas.

Answer 4

Osteoid osteomas arise from proliferation of osteoblasts. Osteoblasts secrete osteoid which then is mineralized by calcium. As such, these tumors present with osteoid surrounded by sclerotic, mineralized bone.

They most commonly present on the cortex of long bones and they’re more common in females younger than 25.

Question 5

What two clinical signs/symptoms can direct you to a diagnosis of osteoid osteoma?

Answer 5

• The bone pain is relieved by aspirin.

* X-rays will show a radiolucent core (the osteoid center) with a sclerotic ring around the outside.

Question 6

How are osteoblastomas different from osteoid osteomas?

Answer 6

Both arise from proliferation of osteoblasts, but there are three key differences: (1) osteoblastomas do not respond to aspirin; (2) osteoblastomas arise in the vertebrae while osteoid osteomas arise in the long bones; and (3) osteoblastomas are larger than 2 cm while osteoid osteomas are smaller than 2 cm.

Question 7

What structure is typical of osteochondromas?

Answer 7

There is a lateral projection from the growth plate (because osteochondromas arise from the growth plate) and the distal portion will be cartilage.

Question 8

Osteochondromas can become malignant. When they do, they’re called _______________.

Answer 8

chondrosarcoma

Question 9

Osteosarcomas arise from ____________ cells.

Answer 9

osteoblast

Question 10

Osteosarcomas are most common in _____________.

Answer 10

teenagers and (less commonly) the elderly

Note: the other tumor that has a bimodal distribution like this is craniopharyngioma.

Question 11

Mutations in ___________ riase risk of osteosarcoma.

Answer 11

RB

Question 12

In the elderly, the most common risk factor for osteosarcoma is _____________.

Answer 12

Paget’s disease

Question 13

Paget’s disease has two potential serious complications. One is osteosarcoma, as was mentioned in another card, while the other is _____________.

Answer 13

high-output cardiac failure

Question 14

Where does osteosarcoma most commonly arise?

Answer 14

The metaphysis of long bones

Question 15

What is Codman’s angle?

Answer 15

Osteosarcomas grow outward and ultimately pull the periosteum off of the bone. This leads to a characteristic x-ray sign in which the periosteum makes an acute angle with the bone.

Question 16

What is the hallmark biopsy of osteosarcoma?

Answer 16

Pleiomorphic cells producing osteoid

Question 17

Why are x-rays of osteosarcomas radiolucent? (That is, why does it have the characteristic hollowed-out look?)

Answer 17

Osteosarcomas are osteoblasts secreting osteoid! Osteoid is not yet mineralized, so the x-ray will be lucent.

Question 18

The only tumor that arises in the epiphysis is ______________.

Answer 18

giant cell tumor of the bone

Question 19

Describe Ewing Sarcoma.

Answer 19

• Derived from neuroectoderm (know this!). Because they are neuroectoderm, they are small, round, and have a high N:C ratio.
• “Onion skin” appearance on x-ray from repeated layering of bone on the expanding periosteum
• Arises in the diaphysis
• 11;22 translocation
• Can mimic osteomyelitis because it presents with bone pain, bone swelling, and fever
• Often presents with metastasis
• Responds to chemotherapy well

Question 20

Chondromas typically arise in which part of the bone?

Answer 20

The medulla

The cortex is where osteoid and mineral deposition occurs.

Question 21

Chondromas arise in the ______________ bones.

Chondrosarcomas, however, arise in the _____________ bones.

Answer 21

small bones (often of the hands or feet)

large, central bones (frequently in the pelvis)

Question 22

List the main things to know about metastatic bone cancer.

Answer 22

• Metastases are more common than primary bone tumors.

* Most metastases produce osteolytic lesions, but prostate cancer produces osteoblastic lesions.