Benign Tumors of Unknown Origin

Question 1

A benign giant cell tumor is a tumor of ____ origin

Answer 1

Unknown

Question 2

A giant cell tumor is also called ____

Answer 2

Osteoclastoma

Question 3

What age group is primarily affected by osteoclastomas?

Answer 3

20-40 years

Question 4

Most giant cell tumors are (benign/malignant)

Answer 4

Benign (80%)

Question 5

The term, ____ refers to giant cell tumors being born malignant, rather than undergoing malignant degeneration.

Answer 5

Quasimalignant

Question 6

What are giant cell tumors comprised of?

Answer 6

• Osteoclastic multinucleated giant cells with proliferating mononuclear cells
• Multiple hemorrhagic areas

Question 7

What is the gross appearance of a giant cell tumor?

Answer 7

Blood-filled sponge

Question 8

What 2 tumors are described by a “blood-sponge” appearance?

Answer 8

giant cell tumor
aneurysmal bone cyst

Question 9

How does the appearance of a giant cell tumor differ from an aneurysmal bone cyst?

Answer 9

giant cell tumor is less hemorrhagic and has less chambers than an ABC

Question 10

Neoplastic cells of a giant cell tumor express high levels of ____

Answer 10

RANKL

Question 11

What does RANKL do?

Answer 11

• promotes proliferation of osteoclast precursor
• effects expression of RANK which leads to differentiation of mature osteoclasts

Question 12

Describe the Pathogenesis of a giant cell tumor

Answer 12

• high levels of RANKL
• ^osteoclast proliferation
• localized, highly destructive resorption of bone matrix
• usually solitary lesions, but may be multicentric/multilocular

Question 13

What is the typical pattern of destruction of a giant cell tumor?

Answer 13

Geographic lytic

Question 14

What is the preferential location of giant cell tumors?

Answer 14

• Arise in metaphysis and extend into epiphysis
• 50% around knee (dist. femur, prox. tibia)
• distal radius, humerus, fibula

Question 15

What is the term for a tumor that extends into the epiphysis of a bone?

Answer 15

Subarticular extension
(Arise in metaphysis, extend into epiphysis)

Question 16

Giant cell tumors spare ____ bone

Answer 16

subchondral (subarticular) bone

Question 17

Where do malignant giant cell tumors tend to metastasize to?

Answer 17

Lungs

Question 18

How can you tell the difference between a benign and malignant giant cell tumor?

Answer 18

appear the same, need a biopsy to tell

Question 19

What is the likely outcome of malignant giant cell tumors?

Answer 19

• often spontaneously regress
• rarely fatal

Question 20

How would a patient with a giant cell tumor present clinically?

Answer 20

• non-specific regional pain (bone pain)
• patho Fx
• joint pain + decreased ROM
• possible functional disability

Question 21

How would a giant cell tumor present differently from an enchondroma?

Answer 21

Painful
(Enchondroma generally asymptomatic)

Question 22

What are the radiographic characteristics of a giant cell tumor?

Answer 22

• geographic lytic lesion
• narrow/short ZoT
• IF expansile, bone surrounding lesion is very thin
• frequently multiloculated

Question 23

What causes the multiloculated appearance of a giant cell tumor?

Answer 23

Endosteal bone resorption

Question 24

What is the treatment for a giant cell tumor?

Answer 24

• curettage (may recur if not clean margins)
• Denosumab (RANKL inhibitor)

Question 25

What is the result of Denosumab on a giant cell tumor?

Answer 25

RANKL inhibitor shrinks tumor

Question 26

Which of the following is NOT a bone forming tumor?
A) enchondroma
B) osteoid osteoma
C) osteochondroma
D) osteoma

Answer 26

A

Question 27

Which benign lesion is most likely to have pain?
A) osteoma
B) enostoma
C) osteoid osteoma
D) osteochondroma

Answer 27

C

Question 28

What 3 pathologies would you include in your differential diagnosis if you see a radiolucent lesion with a sclerotic border?

Answer 28

• Fibrous cortical defect
• Simple bone cyst
• Osteoid osteoma
• enchondroma (sometimes)