Theme 12 - disorders of bone Flashcards
What are 2 developmental lesions that create swellings in the jaw?
Torus palatinus and torus mandibularis
What is a reactive lesion that create swellings in the jaw?
Reactive exostosis - projections from alveolus following chronic trauma e.g. ill fitting denture
What is an osteoma?
Generic tern for a benign bony mass in the jaw. Radiodense, circumscribed lesion.
What are the a) histological types, b) clinical types and c) locations of osteomas?
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)
What are the clinical effects and treatment of a solitary osteoma?
Pressure on adjacent structures
Surgical intervention required as will continue growing
Why are multiple osteomas and odontomes a concerning feature to find on a DPT?
Gardner syndrome - develop polyps in bowel, high risk of malignant change
What are the clinical features of benign neoplasms of the jaw such as ossifying fibroma, osteoblastoma, osteoid osteoma, chondroma, osteochondroma, chondromyxoid fibroma?
Rare
Slow growing
Circumscribed
Mimic cysts on radiographs
What is the most common and second most common malignant neoplasms of the jaw?
SCC arising form oral mucosa invading bone
Metastatic carcinoma
Name three types of primary bone tumours (rare)?
Osteosarcoma
Chondrosarcoma
Mesenchymal chondrosarcoma
What are the features of an osteosarcoma?
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
What is characteristic in the formation of fibrous osseous lesions?
Trabeculae formed in haphazard way and not orientated to mechanical stress
What are the 3 clinical forms of the genetic disorder fibrous dysplasia?
Monostotic (solitary lesion)
Multiple (cranio-facial lesion)
Polyostotic (McCune-Albright syndrome)
What are the features of the McCune-Albright syndrome type of Fibrous dysplasia?
Multiple bone lesions of fibrous dysplasia throughout skeleton
Cafe-au-lait spots
Hormonal abnormality
GNAS mutation - full germline mutation
What are the features of the monostotic and craniofacial types of fibrous dysplasia?
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
What are the histological features of fibrous dysplasia?
Bone present in elongated linear patterns, curved trabeculae and elsewhere irregular
What is the management of fibrous dysplasia?
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
What is an ossifying fibroma?
Benign slow growing lesion affecting mandible>maxilla. On radiograph: Ground glass radiolucency, well circumscribed
Progressive growth and displaces adjacent structures
What is the treatment for an ossifying fibroma?
Surgical removal, clear margins, conservative removal (low chance of recurrence)
What are the histological features of an ossifying fibroma?
Fibroblastic background with trabecular bone forming, similar to fibrous dysplasia
What is cemento-osseous dysplasia?
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
What is a risk with a patient undergoing XLA if they have cemento-osseous dysplasia?
Osteomyelitis (dry socket)
What is the treatment of cemento-osseous dysplasia?
No treatment, avoid inappropriate endodontics and maintain good oral health
What are the characteristic features of cherubism?
Swelling of the lower face at 3-4 years, develops into ‘facies’
Mandible and maxilla affected
Multilocular cystic lesions bilaterally
Submandibular lymph nodes enlarged
What are the histological features of cherubism?
Presence of area of scattered multinucleated osteoclast like cells
Hylanised thick walled vessels running through lesion
What is the role of osteocytes in bone?
Mechanoreceptors withing bone so sense physical stress, osteocytes can slip out of its lacuna and become an osteoblast when bone remodelling reaches it
What is the structure of osteoclasts and what are they?
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
What is the important of RANK Ligand (RANKL)?
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
What are the key histological features of giant cell lesions of the jaw?
- Multi focal arrangement
- Spindle cells
- Red cell extravasation
- Multinucleated osteoclasts
- Rich vascular background
- Mononuclear precursors
- Haemosiderin deposits
