Bone Cysts & Tumor-like Bone Pathologies Flashcards
What are alternative names for a simple bone cyst?
Unicameral or solitary bone cyst
Is a simple bone cyst neoplastic?
No
In short, what is a simple bone cyst?
Disturbance of bone growth following trauma
When in life do 80% of simple bone cysts occur?
Before age 20
Which sex more often experiences simple bone cysts?
Male > Female (3:1)
Where in the body are simple bone cysts most likely to occur?
Metaphyses of:
- Humerus
- Femur
- Tibia
How does trauma lead to a simple bone cyst?
- Hematoma forms and resolves –>
- Body attempts to resolve trauma and forms a fibrous lining –>
- Fibrous tissue pulls serous fluid into lesion –>
- Fluid pressure leads to bone resorption –>
- Reactive bone formation –>
- Lytic lesion with a thin, well-defined margin and sclerotic border
After trauma, the body has formed fibrous lining which pulls serous fluid into the lesion. The fluid pressure leads to bone resorption and some reactive bone formation has occurred. There is now a lytic lesion with a thin, well-defined margin and sclerotic border.
What pathology is present?
Simple bone cyst
Is a simple bone cyst a true cyst?
No, there is no distinct cell lining
A simple bone cyst is never greater in diameter to ___
the growth plate
Which cells are present in a simple bone cyst?
Osteoclastic giant cells, macrophages, and chronic inflammatory cells
Osteoclasts present in advancing area of cyst
What are the radiographic clinical manifestations of a simple bone cyst?
- Unilocular radiolucent lesion with sclerotic border
- Usually centrally located
What are symptoms someone with a simple bone cyst may experience?
- Generally asymptomatic
- Pathological fracture
What are some treatments for simple bone cysts?
- Intralesional corticosteroids
- Curettage and bone grafting
- May reoccur
Aneurysmal bone cysts usually affect individuals ___ years of age
<20 years of age
What is the distribution of aneurysmal bone cysts amongst sexes?
Male = Female
If aneurysmal bone cyst is caused by USP6 overexpression, leading to increase in proteases and transcription factors that upregulate cystic resorption of bone, it is ___
primary
If aneurysmal bone cyst develops with other primary tumors such as giant cell tumors, it is ___
secondary
What makes aneurysmal bone cyst primary?
USP6 overexpression
Increased proteases and transcription factors upregulate cystic resorption of bone
What is the gross appearance of aneurysmal bone cysts?
- Multiloculated lytic lesion with septa composed of fibrous tissue and reactive bone
- Filled with blood
- Resembles a sponge permeated with blood and clots
If bone appears as a sponge permeated with blood and blood clots, what is suspected?
Aneurysmal bone cyst
Aneurysmal bone cysts grow in what nature?
- Rapidly
- Very large
- Central or eccentric
- Expansile (enlarges bone)
As aneurysmal bone cysts enlarge bone, ___ remain intact and ___ thins
periosteum and cortex remain intact and cortex thins
Is pathological fracture more common with a simple or aneurysmal bone cyst?
Simple bone cyst
What are some symptoms someone with aneurysmal bone cyst may experience?
- Pain
- Swelling
- Cyst blows out and causes local hemorrhage
- Neurological deficits possible
How does aneurysmal bone cyst appear radiographically?
- Geographic lytic lesion
- Multilocular
What are some treatments for aneurysmal bone cyst?
What are the recurrence rates?
- Curettage and bone grafting
- Variable recurrence rate (20-70%)
Fibrous cortical defect is 3 tumors for the price of one:
<8 =
8-19 =
20+ =
<8 = fibrous cortical defect
8-19 = non-ossifying fibroma
20+ = fibrous xanthoma
How common is fibrous cortical defect?
Very common: 30% of children
Where in the skeleton is fibrous cortical defect most commonly seen?
Metaphyseal region of tibia or femur
What are the symptoms of fibrous cortical defect?
- Usually asymptomatic
- Sometimes pain (thin cortex)
- Pathologic fractures
Fibrous cortical defects may be associated with which other conditions?
- Neurofibromatosis type 1
- Jaffe-Campanacci syndrome (cafe au lait spots)
What are radiographic characteristics of fibrous cortical defects?
- Cortical location
- Eccentric
- Well-defined margin
- Scalloped margin
- Radiolucent lesion with sclerotic border
If a patient has the following radiographic findings, what is suspected?
- Cortical location
- Eccentric
- Well-defined margin
- Scalloped margin
- Radiolucent lesion with sclerotic border
Fibrous cortical defect
What are some treatments for fibrous cortical defect?
- Spontaneous resolution (replaced by normal bone)
- Curettage and bone grafting (for expanded or symptomatic lesions)
- Fracture repair
When is the onset of fibrous dysplasia?
Children/young adults, usually prior to age 10
What is the etiology of fibrous dysplasia?
- Mutations of GNAS1 gene
- Abnormal cellular development
What are the forms of fibrous dysplasia?
- Monostotic (75%)
- Polyostotic
- McCune-Albright syndrome
Fibrous dysplasia is marked by the failure to ___
form mature lamellar bone in the lesion
Fibrous dysplasia begins as a focal, slowly expanding lesion
It consists of:
- Fibroblasts
- Collagen
- Irregular trabeculae
- Cystic degeneration
- Some hemorrhage
If the following are found in a patient’s bones, what is suspected?
- Fibroblasts
- Collagen
- Irregular trabeculae
- Cystic degeneration
- Some hemorrhage
Fibrous dysplasia
___% of fibrous dysplasia undergo malignant transformation
<1%
Which malignant transformations may occur with fibrous dysplasia?
- Osteosarcoma
- Chondrosarcoma
- Fibrosarcoma
What are the radiographic characteristics of fibrous dysplasia?
- Well-defined margins
- Geographic lytic lesions (well defined borders with thin cortex)
- Enlargement of bone
- Deformation of bone
- Ground glass matrix (uniform density)
If a patient has the following radiographic characteristics, what is suspected?
- Well-defined margins
- Geographic lytic lesions (well defined borders with thin cortex)
- Enlargement of bone
- Deformation of bone
- Ground glass matrix (uniform density)
Fibrous dysplasia
Monostotic fibrous dysplasia is most frequently seen in ___ year old patients
10-30
What is the distribution of monostotic fibrous dysplasia amongst sexes?
Males = Females
What are clinical manifestations of monostotic fibrous dysplasia?
- Asymptomatic
- Incidental finding
- Bone enlargement or deformation
- Pathologic fracture
What are the common locations of monostotic fibrous dysplasia?
- Ribs
- Femur (proximal)
- Tibia
- Facial bones
Polyostotic fibrous dysplasia is usually observed at which times in life?
Childhood
Maybe quiescent in puberty
Lesion growth may increase with pregnancy
How is polyostotic fibrous dysplasia distributed among sexes?
Female > Male
How much of the skeleton is affected by polyostotic fibrous dysplasia?
More than 50%
What are some bone deformities seen in polyostotic fibrous dysplasia?
- Size and shape differences
- Bowing of hips
- Limb length discrepancies
- Spine alignment issues
- Pathologic fractures
How might soft tissue be affected by polyostotic fibrous dysplasia?
Mazabraud syndrome: soft tissue myxomas (benign mesenchymal tumors)
What are common locations for polyostotic fibrous dysplasia?
- Femur
- Tibia
- Pelvis
- Foot
- Ribs
- Skull and facial bones
- Upper extremities
- Lumbar spine
- Clavicle
- Cervical spine
Is polyostotic fibrous dysplasia unilateral/monomelic?
Can be either unilateral or bilateral
How does McCune-Albright syndrome affect females?
Precocious puberty in females; premature closure of growth plates, shorter stature
McCune-Albright syndrome is characterized by ___ dysfunction
endocrine
What are some examples of endocrine dysfunction that may cause McCune-Albright syndrome?
- Acromegaly
- Cushing syndrome
- Hyperthyroidism
- Vitamin D resistant rickets
What are the clinical manifestations of McCune-Albright syndrome?
- Asymptomatic
- Incidental finding
- Bone enlargement or deformation
- Pathologic fracture
- Cafe au lait spots on skin with “coast of Maine” borders
What are some treatments for McCune-Albright syndrome?
- Depends on monostotic vs polyostotic
- Curettage
- Fracture repair
- Prevention of deformities
