9 - Bone pathology Flashcards
What are the key components of bone?
- osteon (Haversian system)
- interstitial, concentric and circumferential lamellae
- periosteum
What are Haversian canal?
Bony canal that contains blood vessels
What are volksman’s canal?
Bony canal that runs perpendicular to Haversian canal that contains blood vessel
What cells are contained within lacunae?
Osteocytes
How does bone histology change as it matures?
Becomes less cellular
What stimulates bone remodelling?
- mechanical stimuli
- systemic hormones
- cytokines
What systemic hormones stimulate bony remodelling?
- PTH
- vitamin D3
- oestrogen
How does oestrogen influence bone?
- acts like a brake on osteoclasts
- when oestrogen levels drop, osteoclasts become more active
What special tests can be done for bone biochemistry?
- can’t take biopsy
- serum alkaline phosphatase
- osteocalcin
- PTH
- vitamin D assays
What is a torus?
- developmental exostosis
- palatinus/mandibularis
- thickening of cortical bone
What is osteogenesis imperfecta?
- type 1 collagen defect
- inheritance varied
- weak bones, multiple fractures
- associated with dentinogenesis imperfecta
What is achondroplasia?
- autosomal dominant condition
- poor endochondral ossification
- causes dwarfism
What is osteopetrosis?
- lack of osteoclast activity
- bone fails to resorb and marrow is obliterated
- bone becomes very dense like stone
What is fibrous dysplasia?
- uncommon gene defect
- slow growing, asymptomatic bony swelling where bone is replaced by fibrous tissue
- stops progressing after growth period
What are the different types of fibrous dysplasia?
- monostotic
- polyostotic
- syndromic (Albright’s syndrome)
What is monostotic fibrous dysplasia?
- single bone (continues to grow)
- most common phenotype
- maxilla>mandible
- causes facial asymmetry
What is polyostotic fibrous dysplasia?
Many bones affected by fibrous dysplasia
What is Albright’s syndrome?
Characterised by multiple bones with fibrous dysplasia, early puberty and increased melanin pigment
Describe the radiographic appearance of fibrous dysplasia.
- “ground glass”, “cotton wool”, “orange peel”
- lacks trabecular pattern
- margins blend into surrounding bone
- bone maintains approximate shape
- becomes more radiopaque as lesion matures
Describe the histology of fibrous dysplasia.
- “fibro-osseous” lesion
- fibrous replacement of bone
- cellular fibrous tissue around metaplastic or woven bone which increases in density
- no capsule
What is rarefying osteitis?
- localised loss of bone in response to inflammation
- process rather than disease
- occurs secondary to another form of pathology
- if at apex of tooth, consider apical periodontitis, periapical granuloma or periapical abscess
What is sclerosing osteitis?
- localised increase in bone density in response to low grade inflammation
- most common around apex of tooth with necrotic pulp
- periapical radiopacity that is poorly defined
- can cause external root resorption
What is idiopathic osteosclerosis?
- localised increase in bone density of unknown cause
- most common in premolar/molar region of mandible
- asymptomatic
- no bony expansion or effect of adjacent structures
What is alveolar osteitis?
- dry socket
- complication of extraction
- causes severe pain, loss of clot and bone sequestra
What is osteomyelitis?
- endogenous infection
- acute or chronic (suppuration is rare)
- presents similarly to sequestra, actinomycosis, chronic diffuse sclerosing osteomyelitis or periostitis
What is Garre’s sclerosing osteomyelitis?
- only seen in children
- any infection can cause
- suppuration present
- painful hard swelling
What are the different aetiologies of bone necrosis?
- osteomyelitis
- avascular necrosis (age related ischaemia or anti-resorptive medication)
- irradiation (ORN)
What are the different types of metabolic bone disease?
- osteoporosis
- rickets/osetomalacia
- hyperparathyroidism
What is osteoporosis?
- bone atrophy (resorption>formation)
- endosteal net bone loss
- quantitive deficiency (bone that is formed is normal)
- symptomless, weak bones, sinus enlargement
What are the radiographic features of osteoporosis?
Loss of normal bone markings
What is the aetiology of osteoporosis?
- sex hormone status
- age
- calcium status and physical activity
- secondary osteoporosis caused by hyperparathyroidism, cushings, thyrotoxicosis, diabetes, long term steroids
What is rickets/osteomalacia?
- rickets in children, osteomalacia in adults
- osteoid forms but fails to calcify
- qualitative deficiency
What is the aetiology of rickets/osteomalacia?
Vitamin D deficiency
How does rickets present?
- children with bow legs
- poor endochondral bone
- law calcium and raised alkaline phosphatase
What is hyperparathyroidism?
- increased levels of parathyroid hormone
- calcium is mobilised from bones causing generalised osteoporosis, brown tumours and metastatic calcification in kidneys
What are the different types of hyperparathyroidism?
- primary (neoplasia/hyperplasia)
- secondary (hypocalcaemia due to vit D deficieny)
- tertiary (hyperplasia due to prolonged secondary)
What is the incidence of primary hyperparathyroidism?
- 1 in 100
- postmenopausal women
- 3:1 F:M
- 90% caused by parathyroid adenoma
What is osteitis fibrosa cystica?
- aka brown’s tumour
- giant cell lesions which with mulitnucelated giant cells and blood vessels which give brown colour
What are the different types of giant cell lesion in the jaw?
- peripheral giant cell epulis
- central giant cell granuloma
What is a central giant cell granuloma?
- grows along jaw
- mandible>maxilla
- 10-25 years
- central lesion may “burst” out which is first clinal sign
What is cherubism?
- rare condition in children
- autosomal dominant inheritance (FH important)
- multicystic/locular lesions in multiple quadrants
- grow before 7 years then regress after puberty
- vascular giant cell lesions
What is the management of cherubism?
- no active management
- may require orthodontic treatment to realign once condition is resolved
What is Paget’s disease?
- presents with bone swelling, pain and nerve compression
- unknown aetiology
- monostotic or polystotic
- > 40 years M>F
Describe the radiographic appearance of Paget’s disease.
- bone pattern changes as disease progresses
- osteoporotic in early stages, becoming osteosclerotic in mature disease
- causes loss of lamina dura, hypercementosis and migration
Describe the histology of Paget’s disease.
- active increased bone turnover
- osteoblastic and osteoclastic activity next to each other which indicates disordered turnover
What are the complications of Paget’s disease?
- infection
- pathological fracture
- tumours (osteosarcoma)
What is an osteoma?
- solitary bone tumour
- if multiple, consider Gardner syndrome which has high polyp cancer risk
What is an osteoblastoma?
- rare bone tumour
- very active growth
What is an ossifying fibroma?
- slow growing bone tumour
- affects wide age range
- mandible
- radiologically well defined as has capsule
Describe the histology of an ossifying fibroma.
- cellular fibrous tissue
- immature bone
- acellular calcifications
What are the different types of cementum lesions?
- cementoblastoma
- cemento-osseous dysplasia
What is a cementoblastoma?
- neoplasm attached to root
- commonly found in lower 4 anteriors
- histology same as osteoblastoma
- PDL space is continuous on radiograph
What is a cemento-osseous dysplasia?
- not neoplastic
- periapical COD (lower 4 anteriors)
- focal COD (one)
- florid COD (all quadrants)
- starts as radiolucency then calcifies
What complication is associated with cemento-osseous dysplasia?
Risk of osteomyelitis if extraction is carried out in area of COD
What is an osteosarcoma?
- rare tumour
- 30s, if older Paget’s related
- mandible>maxilla
- local destruction
- recurrence is high and metastasis common
