Benign Fibro Osseous Lesions of the Jaw

Question 1

What is the classification for benign fibro osseus lesions?

Answer 1

Modified Eversole 2008 1. Bone dysplasia A - fibrous (i)monostotic, ii) polycystic, iii)poly eith endocrinopathy, iv) osteofibrous dysplasia) B - pagetoid heritable bone dysplasia of childhood 2. Cementossues dysplasia A - focal B - florid 3. Metabolic - giant cell over all PTH 4. Neoplastic lesions - ossifying fibroma NOS

Question 2

What causes fibro osseus lesions to form?

Answer 2

Pathological ossification and calcification due to hupercellular fibroblastic marrow. GNAS mutation (ostepprogenator) > increase in camp > cell proliferation with defects in differentiation.

Question 3

What is fibrous dysplasia?

Answer 3

-A bone dysplasia. -Benign replacement of bone marrow with fibrous tissue and woven bone. - GNAS defect. Increased trubecular bone and decreases cortical bone. Also increase in tyronine which increases melanocyte activity. Mono, poly, poly with endocrinopathy.

Question 4

What is the monostotic variant of fibrous dysplasia?

Answer 4

Most common of the lesions in the H&N <20 years, with asymmetry detected later in life. Seen in jaws, frontal, ethmoid and clavicles.

Question 5

What is the monostotic variant of fibrous dysplasia lool like radiographjcally?

Answer 5

Stage dependant . Initially small radiolucency > ground glass mixed latency > diffuse blend with surrounding bone.

Question 6

What is the monostotic variant of fibrous dysplasia histologically?

Answer 6

Stage dependant 1. Thin ostoid with surrounding osteoblasts proliferating hyper cellular stroma layer. 2. Trubecular thickens and woven collagen occurs 3. Woven bone replaces. Mosaic pattern with reversal lines.

Question 7

How does polystotic variant of fibrous dysplasia differ from monostotic?

Answer 7

Multiple bones involved

Question 8

What is the polystotic with endocrinopathy variant of fibrous dysplasia?

Answer 8

MACUNE ALBRIGHT SYNDROME (MAS) GNAS alpha sub unit G protein encodes for Camp which increases expression on IL6 which stimulates osteoclasts.

-Multiple lesions and cafe au lait lesions and endocrine involvement.

Question 9

What are cafe au lait spots?

Answer 9

Collection of melanocyte (light brown) in dermis. Usually doesn’t croas midline. Usually associated with precocious puberty, hyperthyroidism, GH excess (GNAS), cushings syndrome, vitiligo.

Question 10

How do you diagnose and manage fibrous dysplasia?

Answer 10

1. History and examination (onset, pattern, endocrine, cafe au lait, dental exam 2. Imagine (CT/CBCT) ground glass. Full body exam 3. Biopsy (ground and histopath) 4. Referral to endocinolgist 5. Surgical. Stage/age. Monitor annually. If not aggressive debulk. If aggressice debulk to preserve function.

Question 11

What is pagets disease?

Answer 11

Bone dysplasia, can he giant cell related of osteoclastic monocytic reactive origin of lesions. Focal disorder of bone metabolism with overexpression and growth. (Chronic excessive remodeling) 11% of 80, with male predilection. Pathogenesis: osteop, tnfrsf11a, PDB pathway intrucption. or RANKL pathway. P62. Classic and juvenile forms

Question 12

What is the classical form of Paget’s disease?

Answer 12

-Adult onset. -More lucent/ground glass appearance, osseous expansion with bowing and spine curvature -Increase in serum alkaline phosphate but Ca and PTH normal. Hypercementosis of the premolars and molars

Question 13

What is the radiographic appearance of classical pagets?

Answer 13

Appears as: 1. osteoporosis circumscripta: large, well-defined lytic lesions involving the inner aspect of the outer table of the skull (stage one) with a preserved inner table. 2. cotton wool appearance: mixed lytic and sclerotic lesions of the skull. 3. diploic widening tam o’shanter sign: frontal bone enlargement, with the appearance of the skull falling over the facial bones, like a tam o’shanter hat

Question 14

What is the histological findings of classical pagets?

Answer 14

• cellular fibrosis with minimal calcified osteoid. -odontoblastic rimming and osteoclast activity. -MNC in fibrocellular foci and mosaic trabecular pattern -reversal lines from osteoclast enlargement and resting. (may have CGCG or PGCG involvement)

Question 15

How is classical Pagets Diagnosed and treated?

Answer 15

DX:Serum ALP, imaging and biopsy. Tx: Ease pain, Bisphos/RANK L to reduce remodeling MRONJ risk

Question 16

What is the Juvenile form of Pagets?

Answer 16

-Idiopathic Hyperphosphatasemia -Aggressive form, autosomal recessive. -Affects the long bones (bowing due to rapid turnover leading to osteopenia), children/infants - increased ALP, thickening and risk of pathological fracture. -

Question 17

How does Juvenile pagets occur?

Answer 17

-Pathogenesis: TNF-RFSF11B - aspartate lost and osteoclasts not suppressed. -can be self limiting at puberty.

Question 18

What is cemento-osseous dysplasia?

Answer 18

Vital teeth 1-Periapical Cementoossifying Dysplasia (PCOD) - and Focal cemento ossifying dysplasia (FCOD) - very similar 2- Florid cemento ossifying dysplasia (FlCOD) PCOD/FCOD: most common fibrous lesion, apical of one or more teeth. mixed radiolucency (no halo). Females mid30s. mandible/apicals (70%) FlCOD: multiple non expansive radio opaque lesions. 2+ quadrants. Females >45 premolar/molars in mandible. if infected will present as osteomyelitis/cystic changes

Question 19

What is the treatment for What is cemento-osseous dysplasia florid and focal?

Answer 19

regular check ups, if expansive consider other diagnosis and potential biopsy to rule out ossifying fibroma.

Question 20

What is cemento-osseous dysplasias histology findings?

Answer 20

Early, intermediate and late lesions. -Early (osteolytic): well defined vascular fibrous stroma with possible osteoblasts and hemorrhage. vital teeth - Intermediate (osteofibrotic): vascular stroma becomes fibrous with osteoid with ovoid calcification in PDL. -Late (poorly defined): ginger root shaped cementum mass

Question 21

What are the neoplastic fibro-osseus lesions?

Answer 21

progressive proliferative with bony expansion and well defined margins. -Ossifying fibroma/cemento ossifying fibroma NOS -HRPT2 gene (parafibrinprotein). -radiolucent non calcified osteoid > calcification of tumour = radio opaque. -B/L expansion, asymptomatic, displaces teeth and invades antrum. small irregular osteoid with rim of odontoblasts, hypercellular stroma, and woven bone particles.

Question 22

What are Juvenile ossifying fibroma? neplastic

Answer 22

Aggressively and locally destructive 3 variants: 1. Passamamatoid variant 2. trabecular variant 3. Familiial giganitiform cementoma

Question 23

What is Passamatoid variant of ossifying fibroma?

Answer 23

16-30 yrs , orbits

Question 24

What is Trabecular variant of ossifying fibroma?

Answer 24

Children, invades antrum, asymptomatic but rapid expansion. cell rich stroma containing osteoid, trabecular with rimming of giant cells and long plump immature ostoid strands. uncapsulated and has bony infiltrate - mixed well defined radiopacity

Question 25

What is familial gigantiform cementoma of ossifying fibroma?

Answer 25

-children, asymmetry, not limited to apex. -usually a family history -multifocal massively deformative lesion usually in 1 quadrant. -presents as radiolucent lesions with calcification masses -hypercellular stroma with fibroblsats and mature collagen. mitotic figures absent, with disperded ostoid. psammamtoid calcifications.

Question 26

Work up for fibro osseous lesions

Answer 26