Case Study: Metabolic bone
disease
H.R. vd Berg
Dept Radiology
Kimberley Hospital
25/5/2012
Mrs X
• 74 y old female
• Refered from Springbok (Originally from Port
Nolloth) to Orthopaedics KH
• HT, DM-2
• Pathological right midshaft humerus fracture
• ? Primary bone malignancy
Events:
• 10 July – Fractured arm
• 11 July – Seen in Springbok & referred to Kimberley
• 15 July – Admitted by Ortho
– Xrays done
– Bloods: s-ALP 482(↑), CRP 16.7(↑), Normal FBC, UEC, LFT,
CMP.
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18 July ?Paget’s
21 July - Intern Med consult
22 July – Radiology consult
1 Aug – Bone scan
12 Aug – ORIF
15 Aug – D/c
Bone Scintogram:
Paget’s disease: (Osteitis
deformans)
• Sir James Paget 1877
• Multifocal chronic skeletal disease characterized by disordered &
exaggerated bone remodelling leading to weak & deformed bone
• Disease of osteoclasts – too many with lots of nucleoli
• Etiology:
– Genetic (20%):
• Autosomal dominant
• Earlier onset, more bones involved, more
deformities & fractures
– Viral:
• Based on clusters of disease in people exposed to
unvaccinated animals & nuclear material resembling
Paramyxo viral RNA found in osteoclasts
• ? Role of viral infection in genetically susceptible people
• Average onset: 45-55y (Unusual < 40y); 3M:2F
• More prevalent in Northern Europe, North America & Australia
Clinical manifestations:
Asymptomatic (1/5)
Fatigue
Pain + tenderness
Primary process
Pathological fractures
Malign transformation
Deg joint disease
↑Hat size
Deformity of long bones
Warm involved extremity
Peripheral nerve compression
Neurological (Brainstem compression)
Hearing loss, blindness, facial palsy (Neural foramina
narrowing)
High output CCF (↑Metabol & perfusion)
LAB:
↑s-ALP / bone specific ALP: Osteoblastic act
↑u-Hydroxyproline: Osteoclastic act
Normal Ca & PO (Ca may ↑ if immobilized/fracture)
Usually polyostotic and asymmetrical: pelvis, 75% > femur > skull
> tibia > vertebra > clavicle > humerus > ribs
Stages:
1. Early/ Osteolytic/ “Hot” phase:
Active bone resorption
Lytic lesions with sharp borders destroying cortex
and advance along the shaft (candle flame, blade
of grass)
Start at one end of bone and slowly extend along
the shaft.
Bone marrow is replaced by fibrous tissue and
disorganized trabecular “mosaic” pattern
Flat bones showing lytic lesions
= Osteoporosis circumscripta
2. Intermediate/ Mixed phase:
Mixed lytic & sclerotic
Thickened cortex
Trabecular coarsening
Bowing
Cortical thickening
Sclerosis of iliopectineal & ischiopubic lines
Dense sclerotic periphery & lucent
centre = Picture frame
Partial replacement of end plates by
coarse trabecular bone
Focal patchy densities =
Cotton wool
3. Inactive/ Cool/ Sclerotic phase:
Decreased bone turnover with diffuse sclerosis, cortical thickening & blurred corticalmedullary borders
Different phases may coexist in same bone:
Malignant transformation(<1%):
• Cortical disruption, Extension into soft tissue,
Periosteal reactions, Expansile intramedullary
mass
• Biopsy indicated in monostotic lesions not
which does not have the characteristics of
Pagets/ young pt/ demography not usually
seen
– Osteosarcoma(22-90%)
– Malignant fibrous histiocytoma/
Fibrosarcoma(29-51%)
– Chondrosarcoma(1-15%)
Other complications:
Stress fractures
(banana fractures)
Pathological fractures
Osteoarthritis & Acetabular
protrusio
Collapse with spinal
stenosis
Ivory vertebrae: Metastases, Lymphoma, Paget's
disease, Infection
Basilar invagination(PF ROACH):
• Paget disease
• Fibrous dysplasia
• Rickets
• Osteogenesis imperfecta, Osteomalacia
• Achondroplasia
• Cleidocranial dysplasia
• Hyperparathyroidism, Hurler syndrome
Bone scintogram:
• Sensitivity 94%
• Symptomatic lesions have increased
uptake due to bloodflow & blastic
activity
• Normal scan in sclerotic burned-out
areas
• Marginal uptake in lytic areas
• Used to establish extend &
localization (sites rarely change over
lifetime) as baseline
MR findings:
• For imaging of complications (spinal stenosis,
basilar impression, tumour staging)
• Cortical thickening & Coarse trabeculations
(↓T1&2)
• Decreased medullary cavity(↓T1&2)
• Cyst-like fat filled marrow spaces(↑T1&2)
• Bone widening
Cortical thickening
Coarse trabeculae
Treatment of Paget’s disease:
• Pain relief
• Calcitonin/ Bisphosphonates
– Inh osteoclast activity
• Surgical
– Fractures, deformaties, compression, etc
Differential:
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Metastases
Fibrous dysplasia
Multiple myeloma
Lymphoma
Haemangioma
Hyperparathyroidism
Metastases:
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Multiple bone lesions in pt >50y usually mets
Mostly axial & proximal skeleton
Lytic: Kidney, breast, thyroid, GI
Blastic: Prostate, Breast, Cervix, Ovary, Bladder
Mixed: Any, mostly Breast & Lung
Usually widespread
Cortical destruction & periosteal new bone
formation
Paget’s:
• Extension into soft tissue Thickened cortex & trabeculae
Marrow replacement not mass like
• ↑Uptake on bonescan
No cortical destruction
Usually unilateral
Fibrous dysplasia
• Inability of bone forming tissue to
produce mature lamellar bone
• Peak age: 10-20y
• Expansile marrow lesion
• Groundglass
• No soft tissue involvement
• Thin cortex
• Skull: greater involvement of outer
table
• Usually ↑uptake on bone scan
Multiple myeloma:
• Monoclonal neoplastic proliferation of
plasma cells involving bone marrow
• Peak age: 64y
• Multiple well-defined intramedullary
lytic lesions (“Punched out”)
• Sclerosis rare (usually after treatment)
• Endosteal scalloping of cortex
• Soft tissue mass adjacent to bone
destruction
• Cold on bone scan
Lymphoma:
• Peak age: 35-45y
• Mottled permeative bone
destruction
• 70% Associated soft tissue
component
• Cortical destruction late
• Mixed lytic & sclerotic (“Ivory
bone”)
• ↑Uptake on bone scan
Hemangioma:
• Lytic with radiating trabecular
thickening
• “Honeycomb”, “corduroy” in vertebrae
• Vertical/ radial striations (“Spoke
wheel”) in skull
• Small punctated sclerosis(“Polka dot”)
• May have periosteal reaction/ soft
tissue mass
• Usually spine & calvarium
• Vertebral bodies not enlarged &
endplates well defined
• Moderate uptake on
bone scan
Hyperparathyroidism:
• ↑s-Ca (↑s-ALP in 50%)
• Thin cortices with subperiosteal and subchondral
bone resorption
• Spotty deossification with coarse trabecular
pattern – “Salt & Pepper skull”
• Weak bone – basilar invagination, bowing,
vertebral deformaties, fractures
• Brown tumour (bony replacement by vascularized
fibrous tissue)
• Osteosclerosis – “rugger jersey spine”
• Periosteal new born formation (sometimes
cortical thickening)
• Normal bone scan 80%
References:
• Diagnosis and Management of Paget’s Disease
of the bone, www.uptodate.com, 2012
• Diagnostic Imaging: Orthopaedics, Stoller DW,
2nd ed, 2004
• Orthopedic Imaging: A Practical Approach,
Greenspan A, 4th ed, 2004
• Radiology Review Manual, Dahnert W, 6th ed,
2007
• Primer of Diagnostic Imaging, Weissleder R, et
al, 2007