NOF, SBC, ABC, Intraosseous Lipoma Flashcards
What are the 3 categories of fibrous cortical defect?
- fibrous cortical defect (FCD)
- non-ossifying fibroma (NOF)
- fibrous xanthoma (FX)
How are the categories of fibrous cortical defect differentiated?
age
(all appear the same histologically, just written about at different times & ages)
What is the term for a fibrous cortical defect that occurs in patients younger than 8 years old?
fibrous cortical defect
What is the term for a fibrous cortical defect that occurs in patients ages 8-19 years?
non-ossifying fibroma
(8 - <20)
What is the term for a fibrous cortical defect that occurs in patients 20 years and older?
fibrous xanthoma
What is the preferential location of fibrous cortical defect?
metaphyseal region of long bones:
- distal tibia or femur
- proximal tibia
- humerus
- fibula
How would a patient with fibrous cortical defect (NOF/FX) present clinically?
- usually asymptomatic (no edema on STIR)
- patho Fx (thin cortex) -> pain
- may be associated with neurofibromatosis type 1 & Jaffe-Campanacci syndrome
An 18-year-old patient presenting with multiple non-ossifying fibromas (NOFs) and cafe au lait spots may have what associated condition?
Jaffe-Campanacci syndrome
(associated w/ FCD/NOF/FX)
What are the radiographic characteristics of non-ossifying fibromas?
- “blister of bone” appearance
- cortically based/eccentric (always)
- solitary
- geographic lytic
- multiloculated (soap bubble)
- radiolucent lesion with sclerotic border of healing
- may have fibrous matrix (ground glass)
What periosteal reaction is observed in fibrous cortical defect?
none
Fibrous cortical defect has a ____ zone of transition
short/narrow
What matrix calcification is observed in fibrous cortical defect?
none (purely lytic)
Is there any soft tissue mass involved with fibrous cortical defect? How could you tell?
no
- no mass extending beyond bone
- no (aggressive) periosteal reaction
- no displacement of fascial planes
At what point is a patient with fibrous cortical defect at increased risk of pathologic fracture?
When tumor occupies at least 50% of diameter of bone
If a patient has multiple fibrous cortical defects, non-ossifying fibromas, or fibrous xanthomas, what 2 conditions might you be concerned about?
- neurofibromatosis type 1
- Jaffe-Campanacci syndrome
What is the chance of malignant transformation of a non-ossifying fibroma (/FCD/FX)?
none
What is another term for simple bone cyst?
unicameral bone cyst
(=1 chamber)
What age group is primarily affected by simple bone cysts?
3-14 yrs, keep for life
What is the preferential location of simple bone cysts?
- metaphysis/diaphysis
- prox. humerus (50%, MC)
- prox. femur (25%)
- calcaneus
What pattern of destruction is seen in a simple bone cyst?
geographic lytic
A simple bone cyst has a ____ zone of transition
short/narrow
How does the cortical bone appear in a simple bone cyst?
thinning of cortex due to resorption of bone, may lead to pathologic fractures
Why is a simple bone cyst referred to as a “migrating tumor”?
Lesion tends to develop in metaphysis, and can go into diaphysis with age
(NOT a neoplasia)
What type of periosteal reaction may be present in a simple bone cyst?
solid (non-aggressive)
How would a patient present clinically with a simple bone cyst?
- asymptomatic
- incidental finding, usually due to patho. Fx
What are the radiographic characteristics of a simple bone cyst?
- unilocular/pseudoloculated (pseudoseptated)
- radiolucent lesion with sclerotic border
- expansile
- “fallen fragment” sign
- usually centrally located
What radiographic sign is pathognomonic for simple bone cyst?
fallen fragment sign
(piece of cortex “falls” inside bone)
What age group is primarily affected by aneurysmal bone cysts?
5-20 years
What is the preferential location of aneurysmal bone cysts?
80% occur in metaphyseal region of long bones & in the post. arch of spine
(so basically everywhere)
What are the 2 forms of aneurysmal bone cysts?
- primary
- secondary (develop with other primary tumors)
Are aneurysmal bone cysts typically central or eccentric?
eccentric but can be central
Are simple bone cysts typically central or eccentric?
central
What are the radiographic characteristics of aneurismal bone cysts?
- expansile
- eccentric (or central)
- intact periosteum & cortex, with thinning of cortex (saccular, balloon-like)
- multilocular (soap bubble)
- osteolytic with fine trabeculae
- periosteal buttressing
- may cross physis into epiphysis (rare)
What pattern of destruction occurs in an aneurysmal bone cyst?
geographic lytic
An aneurysmal bone cyst has a ____ zone of transition
short/narrow
How will a patient with an aneurysmal bone cyst present clinically?
- acute pain & swelling
- cyst may blow out and cause local hemorrhage
- patho. Fx (rare)
- possible neurological deficits if in spine
What is periosteal buttressing?
thickened cortex adjacent to lesion as periosteum is stripped & filled in (NOT Codman’s triangle)
What sign on MRI is characteristic of aneurysmal bone cysts?
fluid-fluid level
How would an aneurysmal bone cyst appear on a STIR MRI?
edema in adjacent bone tissue
(indirect indicator of pain)
What differential diagnosis mnemonic would include an aneurysmal bone cyst in the neural arch of the spine?
alphabet soup
(ABC, GCT, OB, OC, OO)
An aneurysmal bone cyst in the spine resembles what other tumor?
osteoblastoma
How would you differentiate an aneurysmal bone cyst from an osteoblastoma in the spine?
ABC more expansile, fluid-fluid level on MRI, <20yrs
What is the recurrence rate of aneurysmal bone cysts in the spine?
50%
What symptom of an aneurysmal bone cyst is specific to the spine?
neurologic signs of stenosis
What age group is primarily affected by intraosseous lipomas?
5-70 yrs
What are the radiographic characteristics of an intraosseous lipoma?
- geographic lucency (not FEGNOMASHIC, very characteristic)
- central target sequestrum (calcification)
What are the preferential locations of intraosseous lipomas?
- calcaneus
- tibial metaphysis
- fibular metaphysis
What would your list of differential diagnoses be for an asymptomatic geographic lytic lesion in the calcaneus with stippled calcification?
- enchondroma
- intraosseous lipoma
- SBC
What would your list of differential diagnoses be for an asymptomatic geographic lytic lesion in the calcaneus with a target sequestrum?
- intraosseous lipoma
- enchondroma
- SBC
What would your list of differential diagnoses be for an asymptomatic, geographic, purely lytic lesion in the calcaneus?
- enchondroma
- SBC
- intraosseous lipoma
Give 3 differentials in order from most to least likely.
- Enchondroma (MC, stippled or lytic)
- SBC (lytic)
- Intraosseous lipoma (target)
Give 3 differentials in order from most to least likely.
- Intraosseous lipoma (target)
- Enchondroma (stippled or lytic)
- SBC (lytic)
Painful swelling of the forearm. Give 3 differentials in order from most to least likely.
- ABC (<20, pain, periosteal buttressing)
- Osteoblastoma (<20, pain, >2cm)
- Fibrous Dysplasia (for life, pain, long lesion long bone)
Name an important radiographic finding. What is the diagnosis?
Subarticular extension (seen best on lat view)
Dx: GCT
Painful lesion in 11 year old boy. What is the most likely diagnosis? What radiographic sign helps narrow this diagnosis?
Dx: ABC
Periosteal buttressing (characteristic, not pathognomonic)
Painless swelling of the arm. What is the most likely diagnosis?
SBC
6 year old patient radiographed for trauma. What is the diagnosis?
Fibrous cortical defect (“blister on bone”, <8 yrs)
11 year old patient radiographed for trauma. What is the diagnosis?
Non-ossifying fibroma (“blister on bone”, 8 - <20 yrs)
