Bone Pathology I - fibro-osseous lesions (fibro-osseous dysplasia)

Question 1

What is Fibro-osseous Lesions?

Answer 1

• Normal bone replaced by cellular fibrous tissue with amounts of woven bone and/or acellular islands of mineralized tissue.

Fibrous tissue can have some trabecular bone formation inside or cementum formation inside

Question 2

2 types of fibro-osseous lesions?

Answer 2

Fibro-osseous dysplasias:

Cemento-osseous dysplasia:

Question 3

Cemento-osseous dysplasia?

• fibro-osseous lesions

Answer 3

• Focal cemento-osseous dysplasia.
• Periapical cemental dysplasia.
• Florid cemento-osseous.
• Gigantiform dysplasia.

Question 4

2 types of Fibro-osseous dysplasias?

• fibro-osseous lesions

Answer 4

• Monostotic fibrous dysplasia.
• Polystotic fibrous dysplasia.
• dependent on how they spread

mono- affects 1 bone

poly - affects multiple bones

Question 5

Monostotic Fibrous Dysplasia occurs where?

Answer 5

most common bones affected Limb, rib, skull particularly
Jaw bones.

• Maxillary lesions are more
  common than mandibular

Question 6

What age does monostotic fibrous dysplasia occur?

Answer 6

Childhood and adolescence

Question 7

What is monostotic fibrous dysplasia?

Answer 7

• Cessation of bone growth
  once skeletal growth stops.
• Reactivation of lesions during
  pregnancy.

Question 8

Clinical presentataion of monostotic fibrous dysplasia?

12 marks

Answer 8

• Gradual painless bony swelling.
• Facial asymmetry.
• More pronounced buccally.
• Increased prominence of the
  cheek in maxillary lesion.
• Displacement of teeth

eye can be protruded form normal location if in the maxilla

• Sinus, zygomatic process and floor of the orbit
  (displacement of the contents) involvement.
• In case of rapid growth, exophthalmos and proptosis.
• mandibular lesions in the molar and premolar regions
• increased jaw depth if the lower border is involved
• malignant, tipping or displacement of teeth
• failure of eruption of involved teeth - effects younger pts, affect eruption

Question 9

Differential diagnosis? (Periapical Cemental Dysplasia)

Answer 9

Periapical granuloma
Radicular cysts
Periapical abscess

Question 10

Differential diagnosis? (Florid Osseous Dysplasia)

Answer 10

Odontogenic keratocysts

Question 11

Name the cemeto-osseous dysplasia and what they affect?

Answer 11

1) focal cemento-osseous dysplasia
- 1 tooth anterior region

2) periapical cemental dysplasia
- multiple teeth, mosty anterior teeth

3) florid cemento-osseous
- whole jaw or whole quadrant of jaw

Question 12

what is more common monostotic or polystotic fibrous dysplasia?

Answer 12

monostotic

Question 13

maxilla or mandible more commonly affected by monostotic fibrous dysplasia?

Answer 13

maxilla

Question 14

if multiple bones are affected by monostotic fibrous dysplasia, what is this called?

Answer 14

craniofacial fibrous dysplasia

Question 15

When does monostotic fibrous dysplasia stop and when can it restart?

Answer 15

cessation of bone growth once skeletal growth stops

reactivation during pregnancy or contraceptive pill

usually self-limiting

Question 16

what is occurring here?

Answer 16

normal bone is replaced by fibrous tissue

distorts bone (swelling)

Question 17

What has occurred here?

Answer 17

monostotic fibrous dysplasia

displacement of teeth

Question 18

radiographic appearance of monostotic fibrous dysplasia?

Answer 18

ill defined borders

gradual transition to normal bone
- earlier lesions radiolucent as bone replaced by fibrous tissue
- the mixed fibrous and been formation
- later radiopaque as lesion and bone formation stop

appearance ranges form radiolucent to mottled to radiopaque

ground glass orange peel or cotton-wool appearance

Question 19

what disease?

Answer 19

monostotic fibrous dysplasia

Question 20

polyostotic fibrous dysplasia affects men or women more?

Answer 20

females more 3 times more

Question 21

what bones does polyostotic fibrous dysplasia affect?

Answer 21

bones of lower limbs, skull, vertebrae, ribs and pelvis

Question 22

do lesions for polystotic fibrous dysplasia arise in both sides of the body?

Answer 22

often only arise in 1 side

Question 23

how can severe cases of polystotic fibrous dysplasia present?

Answer 23

present early due to bony deformities and pathological fractures

Question 24

what syndrome is polystotic fibrous dysplasia associated with?

Answer 24

McCune- albright syndrome

affects mainly females

skin pigmentation

hyperfunction of endocrine glands

precocious puberty

Question 25

histopathology of fibrous dysplasia?

Answer 25

• fibrous tissue with islands of woven bone replaces normal bone
• foci of lamellar bone might be seen
• spheroidal areas of acellular calcified tissue
• fibrous tissue may be cellular or consists of interlacing collagen fibres
• Chinese characters
• trabeculae in jaw lesions may be thicker and blunter

Question 26

what disease has Chinese characters?

Answer 26

fibrous dysplasia (fibro-osseous lesions)

irregular trabeculae

Question 27

what disease is shown?

Answer 27

fibrous dysplasia

highly cellular fibrous tissue

irregular trabeculae

Question 28

pathology of fibrous dysplasia?

Answer 28

at the borders, the abnormal bones fuses with surrounding normal bone

(main difference from ossifying fibroma)

as pt become older and bone stops growing - fibrous issue becomes less cellular and more bone formation and becomes more structure bone formation

woven bone remodelled into lamellar bone as bone matures

Question 29

problem with fibrous dysplasia?

Answer 29

lesiosn fuse with normal bone

difficult to iodentify bornders

Question 30

why it hard to identify borders of fibrous dysplasia?

Answer 30

as lesions fuse with normal bone

Question 31

fibrous dysplasia vs ossifying fibroma?

Answer 31

fibrous dysplasia at the borders, the abnormal bone fuses with surrounding normal bone

look exactly the same as fibrous dysplasia but has well defined borders

Question 32

when can fibrous dysplasia become malignant?

Answer 32

few cases are malignant (fibrosarcoma)

malignant transformation following radiotherapy

Question 33

how to remove fibrous dysplasia?

Answer 33

surgical removal

Question 34

when do fibrous dysplasia lesions expand?

Answer 34

period of growth

• cessation of growth in adulthood

Question 35

aetiology of fibrous dysplasia?

Answer 35

complex pathogenesis

GNAS1 is involved - protein involved in bone turnover

Question 36

management of fibrous dysplasia?

Answer 36

after growth cessation

conservative surgical removal

or antibody therapy to target RANKL, which is over-expressed in fibrous dysplasia as a result if the GNAS1 mutation