Benign Tumors of Unknown Origin Flashcards
A benign giant cell tumor is a tumor of ____ origin
Unknown
A giant cell tumor is also called ____
Osteoclastoma
What age group is primarily affected by osteoclastomas?
20-40 years
Most giant cell tumors are (benign/malignant)
Benign (80%)
The term, ____ refers to giant cell tumors being born malignant, rather than undergoing malignant degeneration.
Quasimalignant
What are giant cell tumors comprised of?
- Osteoclastic multinucleated giant cells with proliferating mononuclear cells
- Multiple hemorrhagic areas
What is the gross appearance of a giant cell tumor?
Blood-filled sponge
What 2 tumors are described by a “blood-sponge” appearance?
giant cell tumor
aneurysmal bone cyst
How does the appearance of a giant cell tumor differ from an aneurysmal bone cyst?
giant cell tumor is less hemorrhagic and has less chambers than an ABC
Neoplastic cells of a giant cell tumor express high levels of ____
RANKL
What does RANKL do?
- promotes proliferation of osteoclast precursor
- effects expression of RANK which leads to differentiation of mature osteoclasts
Describe the Pathogenesis of a giant cell tumor
- high levels of RANKL
- ^osteoclast proliferation
- localized, highly destructive resorption of bone matrix
- usually solitary lesions, but may be multicentric/multilocular
What is the typical pattern of destruction of a giant cell tumor?
Geographic lytic
What is the preferential location of giant cell tumors?
- Arise in metaphysis and extend into epiphysis
- 50% around knee (dist. femur, prox. tibia)
- distal radius, humerus, fibula
What is the term for a tumor that extends into the epiphysis of a bone?
Subarticular extension
(Arise in metaphysis, extend into epiphysis)
Giant cell tumors spare ____ bone
subchondral (subarticular) bone
Where do malignant giant cell tumors tend to metastasize to?
Lungs
How can you tell the difference between a benign and malignant giant cell tumor?
appear the same, need a biopsy to tell
What is the likely outcome of malignant giant cell tumors?
- often spontaneously regress
- rarely fatal
How would a patient with a giant cell tumor present clinically?
- non-specific regional pain (bone pain)
- patho Fx
- joint pain + decreased ROM
- possible functional disability
How would a giant cell tumor present differently from an enchondroma?
Painful
(Enchondroma generally asymptomatic)
What are the radiographic characteristics of a giant cell tumor?
- geographic lytic lesion
- narrow/short ZoT
- IF expansile, bone surrounding lesion is very thin
- frequently multiloculated
What causes the multiloculated appearance of a giant cell tumor?
Endosteal bone resorption
What is the treatment for a giant cell tumor?
- curettage (may recur if not clean margins)
- Denosumab (RANKL inhibitor)
What is the result of Denosumab on a giant cell tumor?
RANKL inhibitor shrinks tumor
Which of the following is NOT a bone forming tumor?
A) enchondroma
B) osteoid osteoma
C) osteochondroma
D) osteoma
A
Which benign lesion is most likely to have pain?
A) osteoma
B) enostoma
C) osteoid osteoma
D) osteochondroma
C
What 3 pathologies would you include in your differential diagnosis if you see a radiolucent lesion with a sclerotic border?
- Fibrous cortical defect
- Simple bone cyst
- Osteoid osteoma
- enchondroma (sometimes)
