Fibrous Dysplasia & NF1 Flashcards
What age group is primarily affected by fibrous dysplasia?
8-14 yrs, keep for life
What are the 3 forms of fibrous dysplasia? Which is most common?
- monostotic (MC)
- polyostotic
- McCune-Albright syndrome
What is fibrous dysplasia?
failure to form mature lamellar bone in the lesion, resulting in fibrous replacement of bony stroma
How common is malignant transformation of fibrous dysplasia, and what would it transform to?
<1% of cases (all 3 forms)
- fibrosarcoma (usually)
- osteosarcoma
- chondrosarcoma
What are the radiographic characteristics of fibrous dysplasia?
- geographic lytic lesions (well-defined borders, thin cortex)
- “rind” of sclerosis (thick)
- loculated, trabeculated
- bony expansion
- bony deformation (Sheppard’s crook)
- ground glass matrix (sometimes purely lytic)
- endosteal thinning & scalloping
- “long lesion in a long bone”
- tends to be central
What is the most common benign tumor of the rib?
fibrous dysplasia
What radiographic feature is characteristic, but not pathognomonic of fibrous dysplasia?
long lesion in a long bone
How would a patient with monostotic fibrous dysplasia present clinically?
- asymptomatic
- patho Fx (incidental finding)
- bone enlargement or deformation
- possible altered gait biomechanics
What are the most common locations of monostotic fibrous dysplasia?
- ribs
- femur
- tibia
- skull (facial bones)
How would a patient with polyostotic fibrous dysplasia present clinically?
- > 50% skeleton effected
- bone deformities (size & shape)
- limb length discrepancies
- spine alignment issues
- patho Fx
- Cafe au lait spots (Coast of Maine borders)
What is the preferential location of polyostotic fibrous dysplasia?
any bone
What is McCune-Albright syndrome?
Polyostotic fibrous dysplasia + endocrine abnormality
What endocrine dysfunctions may present with McCune-Albright syndrome?
- acromegaly
- Cushing syndrome
- hyperthyroidism
- vit D resistant rickets
How does precocious puberty present in females?
- Premature onset of menstrual cycle & secondary sex characteristics (~age 5-8yrs)
- Premature closure of growth plates —> shorter stature
How would a patient with McCune-Albright syndrome present clinically?
- female w/ precocious puberty
- asymptomatic
- patho Fx (incidental finding)
- bone enlargement or deformation
- cafe au lait spots on skin with “coast of Maine” borders
Fibrous dysplasia has a ____ zone of transition
short/narrow
The term “fibrous dysplasia” is referring to which form?
monostotic
What matrix calcification is seen in fibrous dysplasia?
ground glass (or purely lytic)
What form of fibrous dysplasia is exclusive to females?
McCune-Albright syndrome
How would you differentiate bony expansion in fibrous dysplasia from Paget disease?
Paget Dz = 55+
FD = young
What is another name for Neurofibromatosis type 1?
Von Recklinghausen disease
What is the family history of neurofibromatosis type 1?
- 60% have family Hx
- ^amount of penetrance (skips generations)
What tissues are involved in neurofibromatosis type 1?
- neuroectodermal (nerve, skin)
- mesodermal
What is the classic triad of neurofibromatosis type 1?
- Cafe au lait spots (coast of California)
- fibroma molluscum
- osseous deformities (particularly in spine)
What does “coast of Maine” imply about the borders of cafe au lait spots?
- jagged borders
- seen in polyostotic fibrous D & McCune Albright syndrome
What does “coast of California” imply about the borders of cafe au lait spots?
- smooth borders
- seen in NF1
What is a fibroma molluscum?
cutaneous nerve tumor
created rubbery, oyster-like, balled-up lesion on skin
What are the clinical features of Neurofibromatosis type 1?
- 6+ cafe au lait spots (50%)
- fibroma molluscum
- elephantiasis
- focal gigantism
- kyphoscoliosis
- atlantoaxial subluxation
Large neurologic tumors that create a huge soft tissue overgrowth is called _____
elephantiasis
The overgrowth of 1 body part is called _____
focal gigantism
What is the most common bony abnormality seen in Neurofibromatosis type 1?
kyphoscoliosis (nerve tumor deforms spine)
What radiographic finding of Neurofibromatosis type 1 in the cervical spine would be a contraindication to cervical spine adjustments?
^ADI d/t transverse ligament instability
What are the radiologic features of Neurofibromatosis type 1?
- 50% develop skeletal lesions
- kyphoscoliosis (MC)
- posterior vertebral scalloping
- enlarged IVFs (d/t dumbbell neurofibromas)
- intrathoracic meningoceles
- twisted/ribbon ribs
- pseudoarthrosis of tibia (50%)
- multiple NOFs (geo. lytic)
- focal gigantism
If a patient has multiple fibrous cortical defects, non-ossifying fibromas, or fibrous xanthomas, and Cafe au lait spots, what condition might you be concerned about?
neurofibromatosis type 1
43 year old male. What is the most likely diagnosis?
Fibrous Dysplasia (for life, ground glass, rind of sclerosis)
What phrase helps determine the diagnosis in this case?
Long lesion in a long bone
(Dx: Fibrous dysplasia)
What feature of this lesion helps differentiate this from Paget disease?
Pseudofracture on concave side = fibrous dysplasia
What is the diagnosis?
Polyostotic fibrous dysplasia
Patient experienced menarche at 8 years of age. What is the diagnosis?
McCune Albright Syndrome
(Females only)
What is the diagnosis?
Polyostotic Fibrous Dysplasia
(If geo. lytic in rib, think fibrous D)
What radiographic sign is demonstrated?
twisted ribbon ribs
(Dx: NF1)
What 2 skin lesions are associated with this condition?
- café au lait spots
- fibroma molluscum
(Finding: twisted ribbon ribs; Dx: NF1)
What radiographic finding is demonstrated?
Posterior body scalloping
(Dx: NF1)
What radiographic finding is demonstrated?
Enlarged IVFs
(Dx: NF1)
