Download Joint Features

Joint Features
• Solid joints: structural, little movement,
– synarthroses (fibrous); symphyses (cartilage)
• Synovial joints: cavity, movement
– Capsule, ligaments, muscles
– Synovial lining, phagocytic or fibroblast-like cells,
hyaluronic acid lubricant
– hyaline cartilage shock absorber, wear resistant
– chondrocytes synthesise and digest matrix of type 2
collagen, proteoglycans
Osteoarthritis
progressive degeneration of articular cartilage
• Usually age-related and oligoarticular; vertebrae, hips, knees, feet and
hands (DIP, PIP)
• May be secondary to obesity, trauma, or joint disease (haemophilia)
• Pain, morning stiffness, crepitus, decreased movement, root
compression, nerve pressure effectes
• Cartilage degenerates, chondrocytes cluster, increased water, decreased
proteoglycans, fibrillation, fragmentation, joint mice, bone exposed,
fractures, cysts, eburnation, osteophytes (Heberden’s nodes), reactive
synovium, fibrous pannus
• Chondrocytes produce Il-1, TNF alpha, Il-6, prostaglandins
Rheumatoid Arthritis
chronic systemic inflammatory disorder
• 1% of population, majority (x5) women, peak 2040 years
• Involves many sites: skin (rheumatoid nodules),
blood vessels (vasculitis), heart, lungs
• Principally involves joints: hands, feet; later
wrists, elbows, ankles, knees
• Onset: gradual systemic or acute arthritis, swollen,
hot, painful and stiff joints
Rheumatoid Arthritis
• Pathogenesis
– Genetic susceptiblity (HLA Dr4, common motif of antigen binding site of
DR molecule)
– Antigen: microbial? Epstein Barr, mycoplasma, borrelia
– Autoimmunity: to collagen or cartilage proteoglycan, driven by CD4 cells
• Joint damage:
– activated cells cytokine loop,
– B cell activation, IgM autoantibodies to IgG (rheumatoid factor)
– immune complexes
• Effect:
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inflamed synovium, oedema, thickened hyperplastic papillae form
Increased vascularity, lymphocytes, plasma cells, fibrin
Bone eroded, subchondral cysts, osteopenia,
pannus (granulation tissue obliterating synovium); ankylosis
8 other forms of arthritis
• Juvenile rheumatoid arthritis: large joints, oligo
involvement, RF negative, ANA+
• Ankylosing spondylitis, HLA B27, males, axial, sacroiliac
joints
• Reiter syndrome: Arthritis, urethritis, conjunctivitis,
autoimmune reaction following infection of GI or urethra
• Psoriatic arthritis: 5% of sporiasis, like RA
• Infectious: suppurative, tuberculous
• Lyme arthritis: borrelia burgdorferei, late in disease, large
joints
• Gout: uric acid crystals, acute arthritis, chronic tophaceous
arthritis, tophi
• Pseudogout: calcium pyrophosphate, knees
Vitamin D
• Role: bone mineralisation, maintaining serum calcium and
phosphate levels
• Source; skin, 7 dehydrocholesterol (sun) vitamin D3: diet
ergosterol altered to vitamin D2
• Synthesis: travels on binding protein
– to liver (hydroxylase) produces 25 (OH)D
– to kidney (hydroxylase) produces 1.25 (OH)D
• Effects
– GI absorbs calcium and phosphate
– Bone: mobilises calcium phosphate (with PTH)
– Kidney: absorbs calcium, loses phosphate (with PTH)
Rickets and osteomalacia
• Vitamin D deficiency:
• 1) diet (sunlight),
• 2 malabsorption,
• 3 metabolism: liver or kidney disease (cyto P450, renal hydroxylase
deficiency),
• 4 end organ resistance
• Phosphate deficiency (aluminium bound, failed renal tubular
absorption
• Normal growing cartilage - becomes calcified - stops growing endochondral ossification
• Children (rickets): growing cartilage not calcified, abnormal growth
and poor ossification, abnormal bone in skull, ribs, vertebrae, lower
limbs
• Adult (osteomalacia): growth finished, excess osteoid, osteopenia,
fractures
Osteoporosis
• Peak bone mass; effect of vitamin D, diet, exercise,
hormones
• Normal bone remodeling: bone loss less than 1% a year
• Senile osteoporosis: with age, osteoblasts less effective
(diet and exercise influence) increased slow bone loss
mainly in cortex
• Post menopausal osteoporosis: decreased oestrogen allows
increase in cytokines (Il-1, Il-6 and TNF alpha) which
mobilizes osteoclasts; reactive osteoblast mobilisation,
high turnover bone loss, main effects on cancellous bone
• Result: (microfracture) vertebrae—pain, height loss,
deformity; pelvis, hips—fractures (fatal secondary
illnesses; pneumonia, pulmonary embolism)
Hyperparathyroidism
Renal osteodystropy
• Primary or secondary hyperparathyroidism: increased PTH signals
osteoblasts which signal osteoclasts to resorb bone
• Effects:
– Subperiosteal resorption (hand X-ray)
– Dissecting osteitis: resorption, fibrosis, microfractures of cancellous bone
– Brown tumour (osteitis fibrosa cystica, Von Recklinghausen)
haemorrhage, haemosiderin, inflammatory repair, cystic change
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Renal osteodystrophy :
– Renal failure causes defective 1,25 (OH)D, loss of phosphate and
retention of H (acidosis)
– These induce changes of hyperparathyroidism, osteomalacia, osteoporosis,
osteosclerosis and decreased growth. The bone loss may be high, low or
mixed turnover
– Excess aluminium and amyloid may add to the effect
Bone Features
• Bone profile: joint - cartilage - epiphysis - plate - metaphysis diaphysis (shaft)
• Bone section: periosteum - cortical bone - cancellous bone - medulla
• Periosteum: produces reactive bone if stimulated (causes Codman’s
triangle, sunburst, or onion skin patterns on X-ray)
• Osteoblasts, contain alkaline phosphate, become osteocytes, produce
osteoid (like collagen) which becomes mineralised as bone (fibres are
at first irregular - woven - later become parallel - lamellar
• Osteoclast: multinucleated cell of monocyte-histiocyte lineage,
contains acid phosphate, lyses bone.
• Growth: at metaphysis, site of most tumours
• Long bone growth: metaphyses near knee (lower femur, upper tibia)
remote from elbow (upper humerus)
• Effects of age: closure of epiphyses
Bone tumours
• Presentation: pain, tenderness, swelling, deformity,
pathological fracture
• 1) secondary tumours: 70% of cancer involves bone;
spreads to bone by blood or vertebral lymphatics
– Deposits are usually: multiple, in axial skeleton, in the red marrow,
lytic, may sclerotic (prostate, breast)
– (role of vessels, prostaglandins, osteoclast activing factor)
– Effect: hypercalcemia, leukoerythroblastic anaemia
• 2) marrow tumours: Leukaemia, lymphoma, myeloma
• 3) primary bone tumours: benign or malignant
Osteosarcoma
• Primary (70%): 10-25 years, males x 2, some familial or follow
retinoblastoma
• Secondary (30%): paget’s disease, enchondromatosis, chronic
osteomyelitis, fibrous dysplasia, bone infarcts or fractures, radiation
(radium or external), alkalating agents
• Aetiology: ? Virus, immunological, genetic, related to bone mass
• Usual findings: in medulla of long bones at metaphysis, 70% about the
knee as bulky mass
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Codman’s triangle on x-ray
25% have metastases (usually lung) at diagnosis, mean survival 3 years
Variants: may be cortical, periosteal, parosteal, extraskeletal
Microscopy: osteoblastic (but also chondroblastic, fibroblastic,
angioblastic areas)
Chondrosarcoma
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Males x 2, age 50s and 60s
Primary (90%)
Secondary (10%) enchondromas etc. as for osteosarcoma
Presentation: lobulated mass with spotty calcification;
pelvic bone (50%) or other central sites
• Correlation of clinical, x-ray and histopathology essential
(malignant central lesion histologically similar to a benign
peripheral lesion)
• Microscopy: most are low grade (grade 1) 90% 5-year
survival; grade 3 have poor survival (40% 5-year survival)
Ewing’s Sarcoma
• Presentation: Pain, tenderness, swelling, systemic symptoms (may
simulate osteomyelitis), age 5-20, males x 2, involves pelvis or long
bones, 25% have metastases (to lung, brain, other bones) at diagnosis
• Begins in medulla of metaphysis or of diaphysis but spreads to
periosteum producing Codman’s triangle and onion layering effect on
x-ray
• Microscopy: small round cells with cytoplasmic glycogen (PAS+)
• Cell of origin unknown: ?mesenchymal, related to peripheral
neuroectodermal tumour (PNET) which has neural feature; both have
t(11-22), produce a fusion gene EWS-FLI1, stain with antibodies to
CD99
• Survival: has improved from 10% to 75% with modern chemotherapy
Giant cell tumour
• Microscopy: neoplastic stromal cells with prominent giant
cells
• Exclude other lesions which may have giant cells including
brown tumour of hyperparathyroidism, gingival epulis,
fibrous cortical defect, aneurysmal bone cyst,
chondroblastoma. Carcinoma and soft tissue sarcoma may
sometimes have prominent giant cells but rarely cause
diagnostic difficulties
• Occur in epiphysis after closure (age 15-55 years), 50%
about knee, more frequent in females
• Most are benign, one-third to one-half recur, 10% are
aggressive or malignant but such behaviour can not
reliably be predicted histologically
Paget’s disease
• Bone disease with osteoclastic (early), mixed , and osteosclerotic (late)
stages
• May be monostotic or polyostotic; usually involves axial skeleton
• Involves 1-3% of the older population, males (4:3) more frequently
• Prodominantly a disease of people of N European stock, ? Viral cause,
viral type particles in osteoclasts
• Usually asymptomatic (identified incidentally on x-ray or by raised
alkaline phosphatase). Causes excess production of collagen products
(hydroxyproline)
• May cause pain, deformity, nerve pressure, haemodynamic shunting of
blood, pathological fracture, sarcoma
• Therapy: calcitonin, diphosphonates, mithramycin, fluorides
Fibrous dysplasia
• A developmental defect showing impaired bone formation
with disorganised osseous and fibrous tissue which
fractures and causes deformities
• Usually monostotic, ribs, skull, jaw, femur (in teens and
20s)
• In 25% polyostotic (usually children)
• Occasionally (3%) with pigmentation, precocious puberty
(females) and endocrinopathy (hyperthyroidism,
hyperparathyroidism, hyperpituitarism, diabetes) as
Allbright’s syndrome
Other cartilage tumours
Osteochondroma
• Disordered growth from epiphysis to form abnormal metaphyseal spur
• Mainly a sporadic disorder of long bones in adolescence
• Occasionally multiple as an autosomal dominant disorder
• Rarely sarcoma may supervene
Enchondroma
• Sporadic single lesions, may be asymptomatic or cause deformity
• Multiple (enchondromatosis) (Ollier’s disease) as a non-hereditiary
disease involving hand and feet in childhood
• Multiple with multiple cavernous haemangiomas as a familial disease
(Maffucci’s disease)
Rare lesions: Chondromyxoid fibroma, Chondroblastoma
Other bone tumours
Osteoma
• Rare, usually involves face of skull
• Gardner’s syndrome: osteomas with epidermal cysts, teeth disorders,
desmoid tumours, and colonic adenomatous polyps
Osteoid osteoma
• Tiny (3-10 mm) vascular osteoblastic lesion (nidus), regarded as a
benign neoplasm, surrounded by a large reactive osteosclerotic rim
• Larger, histologically similar lesion in vertebrae and lower limbs is
painless (osteoclastoma)
• Causes severe night pain relieved by aspirin, cured by excision
• Age 5-25, males x 3
• Site: metaphysis of long bones especially of lower limb
Cysts
• Simple: solitary fluid-filled lesions in metaphysis near
epiphyseal plate. Two-thirds in proximal long bones, males
x 3, childhood and adolescence
• Aneurysmal bone cyst: blood-filled spaces separated by
fibrous septae distend bone and may extend into
surrounding tissue (may be secondary to degeneration of
another lesion). Involve vertebrae and flat bones (10-20
years; M=F)
• Fibrous cortical defect (non-ossifying fibroma): Defect of
epiphyseal plate growth extending into the metaphysis,
usually about the knee, in children