bone pathology Flashcards
Describe the histological layout of compact bone?
Units are called osteons or a Haversian system
Between these are interstitial lamellae
Blood vessels are found in the Haversian canals
Osteons have concentric lamellae which contain osteocytes
What 3 systemic hormones are involved in bone remodelling?
PTH
Vitamin D3
Oestrogen
What role does PTH play in bone remodelling?
Produced in response to low blood calcium
It acts to increase blood calcium by stimulating bone resorption, releasing calcium and phosphate from bone matrix into the bloodstream
What role forms Vitamin D3 play in bone remodelling?
Enhances the absorption of calcium and phosphate from the diet
Also promotes mineralisation of newly formed bone by stimulating activity of osteoblasts
What role does oestrogen play in bone remodelling?
Inhibits bone resorption by regulating the activity of osteoclasts
It suppresses the production and activity of osteoclasts
What special tests can be carried out for bone biochemistry?
Blood calcium
Osteoblast activity
Osteoclast activity
PTH
Vitamin D assays
What are tori and give examples and clinical relevance?
Developmental exostosis that give problems with fitting dentures
Torus palatinus - midline of palate
Torus/tori - mandibularis
What is osteogenesis imperfecta, what are the clinical features and what is is associated with?
Type 1 collagen defect
Inheritance varied - 4 main types
Clinical features include weak bones and multiple fractures
Sometimes associated with dentinogenesis imperfecta
What is achondroplasia?
An autosomal dominant condition causing poor endochondral ossification
Causes Dwarfism
What is osteopetrosis?
A lack of osteoclast activity causing failure of resorption and marrow obliteration
What is fibrous dysplasia and who is affected?
An uncommon gene defect
Causes a slow growing, asymptomatic bony swelling - bone is replaced by fibrous tissue
Active in those under 20, stops growing after growth period usually
How does fibrous dysplasia present clinically?
Can be monostotic single bone) or polyostotic (many bones)
More commonly monostotic
Affects maxilla more than mandible
Causes facial asymmetry
What are 2 names for the appearance of fibrous dysplasia?
Ground glass appearance
Orange peel appearance
How does fibrous dysplasia appear radiographically?
Margins often blend into adjacent bone
Bone maintains approximate shape (initially)
Becomes more radiopaque as lesions matures
Describe the histology of active fibrous dysplasia
Fibro-osseous
Fibrous replacement of bone - cellular fibrous tissue
Bone is metaplastic or woven but will remodel and increase in density
What is rarefying osteitis and what should be considered as differential diagnoses?
Localised loss of bone in response to inflammation
Always occurs secondary to another form of pathology
If at apex of tooth - consider apical periodontitis, periapical granuloma or periapical abscess
What is sclerosing osteitis, where is it most common and how may it progress?
Localised increase in bone density in response to low-grade inflammation
Most common around the apex of a tooth with a necrotic pulp
May lead to external resorption if chronic
What is idiopathic osteosclerosis, where is it most common and how does it present?
Localised increase in bone density of unknown cause
Also known as dense bone island
Most common in premolar-molar region of mandible
Always asymptomatic
No bony expansion and no effect on adjacent teeth/structures
How can you identify idiopathic osteosclerosis from sclerosing osteitis?
Sensibility test the tooth involved - if no response then Sclerosing osteitis
What is alveolar osteitis and how does it present?
Dry socket
A complication of extraction, particularly difficult lower molars
Severe pain, loss of clot and bone sequestra
Has varied and unknown aetiology
What is osteomyelitis?
A rare endogenous infection that can be acute or chronic
Endogenous - arises from microorganisms present within the body
How does osteomyelitis present clinically and what infections are often seen?
Sequestrum
Actinomycosis - post extraction infection caused by Actinomyces
Chronic diffuse sclerosing osteomyelitis
Periostitis productive (Garre’s sclerosing osteomyelitis) - found in children
Suppuration is rare
Describe the aetiology of bone necrosis
Osteomyelitis - acute or chronic
Avascular necrosis:
- age related ischaemia
- anti-resorptive medication
Irradiation:
- osteoradionecrosis - prone to infections
Give 3 examples of metabolic bone diseases
Osteoporosis
Rickets and osteomalacia
Hyperparathyroidism
What conditions are osteoclast inhibitors used for?
Osteoporosis
Paget’s disease
Bone metastasis
Where is osteonecrosis most found?
Affects the mandible more than the maxilla
60% are related to a dental procedure
How is osteonecrosis managed?
Conservative - extract as a last resort
If established then supportive care
What is osteoporosis?
Bone atrophy - where resorption exceeds formation
An endo steal net bone loss
A quantitative deficiency (bone formed is normal)
What are the clinical features of osteoporosis?
Symptomless
Weak bone
Antrum enlarged
What is the radiographic feature of osteoporosis?
Loss of normal bone markings
What are the aetiological factors for osteoporosis?
Oestrogen deficiency
Age
Calcium status
Physical activity
What is secondary osteoporosis and give 4 causes of it
Caused by an underlying medical condition:
- hyperparathyroidism
- Cushing’s syndrome
- diabetes mellitus
- thyrotoxicosis
What is rickets and osteomalacia?
Vitamin D deficiency - lack of sunlight, poor diet, malabsorption, renal causes
Osteoid forms but fails to calcify
Poor endochondral bone formation
Low calcium
Raised alkaline phosphatase
What is hyperparathyroidism?
Calcium mobilised from bones
Generalised osteoporosis
What are the types of hyperparathyroidism?
Primary - neoplasia/hyperplasia
Secondary - hypocalcaemia (due to vitamin D deficiency)
Tertiary - hyperplasia as a result of prolonged secondary
What is the incidence of primary hyperparathyroidism?
Affects 1 in 1,000
Mainly post-menopausal woman
Affects females over males in 3:1 ratio
90% of these have increased PTH - hypercalcaemia and increased bone turnover
What is osteitis fibrosa cystica?
Generalised osteoporosis
Focal osteopathic lesions
Giant cell lesions (brown tumours)
Give 2 examples of giant cell lesions of the jaws
Peripheral giant cell epulis
Central giant cell granuloma
What is the incidence of giant cell lesions of the jaws?
Age 10-25
Affects mandible > maxilla
What are the 3 differential diagnoses of giant cell lesions of the jaws?
Osteitis fibrosa cystica
Aneurysmal bone cyst
Giant cell tumours (very rare)
What is cherubism?
A rare autosomal dominant inherited condition
Multicystic/multilocular lesions seen in multiple quadrants
Grow before about 7 years then regress after puberty
What is seen histologically in cherubism?
Vascular giant cell lesions
How does Paget’s disease of bone present clinically?
Bone swelling
Pain
Nerve compression
What is Paget’s disease?
Abnormal bone remodelling leading to enlarged and weakened bone
What is the incidence of Paget’s?
Mostly in age >40
Affects males more than females
How does Paget’s present radiographically?
Loss of lamina dura
Hypercementosis
Migration (due to bone enlargement)
Can be monoatomic or polystotic
Describe the histology of Paget’s
Increased bone turnover
Osteoclastic and osteoblastic activity
What are the complications of Paget’s?
Infection
Tumour
Give 2 examples of bone tumours?
Osteoma
Osteoblastoma
Describe an osteoma?
Solitary
Mostly affects cortical bone
Slow growing
If multiple then consider Gardner’s syndrome
How do ossifying fibromas present clinically?
Slow growing
Affects a wide age range
Mainly found in the mandible
Radiologically - well-defined
Histologically - celllular fibrous tissue
Acellular calcifications
Give 2 examples of cementum lesions
Cementoblastoma
Cemento-osseous dysplasias
What is a cementoblastoma?
Neoplasm attached to the root
Histology the same as Osteoblastoma
What is a cemento-osseous dysplasia and name the different types?
A radiolucency which turns into calcification
Types:
- periapical COD
- focal COD
- florid COD
Describe osteosarcomas
Rare
Most common in age 30s - if in elderly then likely Paget’s
Affects mandible > maxilla
Varied clinical and radiographic presentation
Causes local destruction
High recurrence and metastasis
