Theme 12 - disorders of bone

Question 1

What are 2 developmental lesions that create swellings in the jaw?

Answer 1

Torus palatinus and torus mandibularis

Question 2

What is a reactive lesion that create swellings in the jaw?

Answer 2

Reactive exostosis - projections from alveolus following chronic trauma e.g. ill fitting denture

Question 3

What is an osteoma?

Answer 3

Generic tern for a benign bony mass in the jaw. Radiodense, circumscribed lesion.

Question 4

What are the a) histological types, b) clinical types and c) locations of osteomas?

Answer 4

a) Compact (solid bone) and cancellous (inner core is trabecular)
b) solitary and multiple
c) Juxtacortical (periosteal protruding from mandible/maxilla) and Endosteal (protruding into medullary bony cavity)

Question 5

What are the clinical effects and treatment of a solitary osteoma?

Answer 5

Pressure on adjacent structures
Surgical intervention required as will continue growing

Question 6

Why are multiple osteomas and odontomes a concerning feature to find on a DPT?

Answer 6

Gardner syndrome - develop polyps in bowel, high risk of malignant change

Question 7

What are the clinical features of benign neoplasms of the jaw such as ossifying fibroma, osteoblastoma, osteoid osteoma, chondroma, osteochondroma, chondromyxoid fibroma?

Answer 7

Rare
Slow growing
Circumscribed
Mimic cysts on radiographs

Question 8

What is the most common and second most common malignant neoplasms of the jaw?

Answer 8

SCC arising form oral mucosa invading bone
Metastatic carcinoma

Question 9

Name three types of primary bone tumours (rare)?

Answer 9

Osteosarcoma
Chondrosarcoma
Mesenchymal chondrosarcoma

Question 10

What are the features of an osteosarcoma?

Answer 10

Expansive ulcerated mass arising from jaw
It is a malignant neoplasm of osteoblasts, lays down tumour osteoid that is mineralised and shows radiographically as trabeculae - radiates around from bone surface like sun-ray appearance

Question 11

What is characteristic in the formation of fibrous osseous lesions?

Answer 11

Trabeculae formed in haphazard way and not orientated to mechanical stress

Question 12

What are the 3 clinical forms of the genetic disorder fibrous dysplasia?

Answer 12

Monostotic (solitary lesion)
Multiple (cranio-facial lesion)
Polyostotic (McCune-Albright syndrome)

Question 13

What are the features of the McCune-Albright syndrome type of Fibrous dysplasia?

Answer 13

Multiple bone lesions of fibrous dysplasia throughout skeleton
Cafe-au-lait spots
Hormonal abnormality
GNAS mutation - full germline mutation

Question 14

What are the features of the monostotic and craniofacial types of fibrous dysplasia?

Answer 14

Bony hard swelling in jaw
Slow growth, painless
No tooth displacement
No systemic abnormalities
On radiograph- well circumscribed but interface of lesion and bone has no discrete edge/diffuse margin. Ground glass appearance as trabecular bone formed, orange peel as mineralises

Question 15

What are the histological features of fibrous dysplasia?

Answer 15

Bone present in elongated linear patterns, curved trabeculae and elsewhere irregular

Question 16

What is the management of fibrous dysplasia?

Answer 16

Review until skeletal maturity (confirmed with bone scan)
Cosmetic recontouring
Denosumab-targeted therapy against RANK L to stop growth
McCune-Albright syndrome require referral to genetic department

Question 17

What is an ossifying fibroma?

Answer 17

Benign slow growing lesion affecting mandible>maxilla. On radiograph: Ground glass radiolucency, well circumscribed
Progressive growth and displaces adjacent structures

Question 18

What is the treatment for an ossifying fibroma?

Answer 18

Surgical removal, clear margins, conservative removal (low chance of recurrence)

Question 19

What are the histological features of an ossifying fibroma?

Answer 19

Fibroblastic background with trabecular bone forming, similar to fibrous dysplasia

Question 20

What is cemento-osseous dysplasia?

Answer 20

Often an incidental radiographic finding of single or multiple radioluscencies (often confused with PAP) with radiopaque nidus
African heritage, middle age women. Symptomless with no external signs unless advanced which may distort jaw

Question 21

What is a risk with a patient undergoing XLA if they have cemento-osseous dysplasia?

Answer 21

Osteomyelitis (dry socket)

Question 22

What is the treatment of cemento-osseous dysplasia?

Answer 22

No treatment, avoid inappropriate endodontics and maintain good oral health

Question 23

What are the characteristic features of cherubism?

Answer 23

Swelling of the lower face at 3-4 years, develops into ‘facies’
Mandible and maxilla affected
Multilocular cystic lesions bilaterally
Submandibular lymph nodes enlarged

Question 24

What are the histological features of cherubism?

Answer 24

Presence of area of scattered multinucleated osteoclast like cells
Hylanised thick walled vessels running through lesion

Question 25

What is the role of osteocytes in bone?

Answer 25

Mechanoreceptors withing bone so sense physical stress, osteocytes can slip out of its lacuna and become an osteoblast when bone remodelling reaches it

Question 26

What is the structure of osteoclasts and what are they?

Answer 26

Macrophage lineage - function to resorb bone
Sit in scalloped depression called Howships lacuna, oppose mineralise bone surface with brush border where acid and enzymes secreted to dissolve collagenous component of bone

Question 27

What is the important of RANK Ligand (RANKL)?

Answer 27

RANK secreted by osteoblasts binds to osteoclasts by RANK L. Ensures bone remodelling a balanced process and is a pharmacological target to switch osteoclasts off

Question 28

What are the key histological features of giant cell lesions of the jaw?

Answer 28

• Multi focal arrangement
• Spindle cells
• Red cell extravasation
• Multinucleated osteoclasts
• Rich vascular background
• Mononuclear precursors
• Haemosiderin deposits