bone pathology

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bone pathology
2013-07-17 14:50:20

bone pathology
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  1. Congenital diseases of bone
    osteogenesis imperfecta

  2. Osteogenesis Imperfecta
    (Brittle Bone Disease)
    Hereditary or sporadic 

    genetic mutation affecting type I collagen synthesis
  3. Osteogenesis imperfecta: 

    heriditary is the major cause
  4. Osteogenesis imperfecta - bone manifestation
    too little bone

    extreme skeletal fragility: multiple fracture
  5. Ostiogenesis imperfection- manifestation
    bone and extraskeletal manifestation
  6. Osteogenesis imperfecta  - type of bone menifestation
    abnormal: severe, type II and lethal

    Normal: milder, type I: normal lifespan, most common form
  7. osteogenesis imperfecta - clinical presentation
    –Blue sclera in type I

    –Multiple bone fractures (with little force)

    –Early hearing loss

    –Some may have dental manifestation (dentinogenesis imperfecta)

    Severe forms: skeletal deformity
  8. Osteogenesis imperfecta:

    blue sclera is found in OI pt
  9. OI - dx
    Clinical history, X-ray, collagen test, genetic test
  10. child present with multiple fracture. what are the differential dx?
    Child abuse vs OI
  11. Child abuse vs OI
    bone density: child abuse present with normal bone density, OI has lower bone density 

    collagen test
  12. OI - treatment
    only management 

    Low impact exercises

    Surgery and bracing in severe cases

    Genetic and psychological counseling

    • Bisphosphonates (drugs for osteoporosis):
    • controversial
    • •Clinical trial
    • •Not recommended for mild forms
  13. osteoclast development
    from monocyte/ macrphage precuresor which turn into osteoclast precursor 

    in the presence of RANKL and osteoblaststromal cell and M-CSF --> mature
  14. Osteopetrosis - predominant form: hereditary or sporadic
  15. Osteopetrosis - pathophysiology
    • genetic mutation affecting osteoclast fxn
    • --> reduce bone resorption and defectie bone remodeling 

    dense bone: artecturally unsound
  16. Osteopetrosis - clinical presentation

    Reduced hematopoiesis in bone marrow and develop hepatosplenomegaly (low RBC count)

    Infection (low WBC count)

    Cranial nerve problems (compression from bone
  17. Osteopetrosis - txn
    bone marrow transplant
  18. The most common bone disease
  19. Osteoporosis - pathophysiology
    •Bone resorption exceeds bone formation. Decreased bone mass, increased porosity
  20. osteoporosis - most common form
    Senile and postmenopausal osteoporosis
  21. Osteoporosis - cause
    aging and hormone
  22. Senile osteoporosis
    dec in estrogen in women (>50) and testosterone in man (>70)

    normal/inc osteoclast and dec osteoblasts
  23. Osteoporosis - clinical
    Females are more vulnerable

    No specific symptoms

    Lower body weight is a significant risk factor

    Increased risk of fracture
  24. Osteoporosis - significant risk factor
    • lower body weight 
    • aging and menopausal
  25. Osteoporosis - prevention and txn
    Increase the peak bone density before the age of 30

    Diet: Vitamin D, calcium


    Medications:  e.g. bisphosphonate (decreased bone resorption)
  26. Paget Disease of Bone - pathophysiology
    increase bone remodeling 

    activated osteoclast and compensatory osteoblast. these lead to osteolytic stage and mixed osteoblatic-osteoclastic stage 

    bottom line: cells burned out (reduced osteoclast and osteoblast), gain in bone mass, osteosclerotic stage, abnormal bone
  27. Paget disease of bone - histology
    mozaic or jigsaw puzzle appearance
  28. Paget disease of bone - clinical presentation
    • Relatively common, most patients >40 yo,
    • M>F

    • Localized, monostotic (15%), polyostotic
    • (85%)
    • •Skull: increased circumference, hat no longer fit
    • •Jaw: spacing of the teeth or dentures no longer fit

    –Radiograph: depend on stages (middle stage - longest stage), “cotton-wool”

    • –Most run a benign course. However, 1%
    • develop sarcoma

    –Pain is the most common symptom, fracture

    • –May promote OA if close to joint; may develop bowing deformity if involving
    • weight-bearing bone
  29. Paget disease of bone -lab findings
    markers for bone turnover (value depends on the stage)

    •Alkaline phosphatase (serum)

    •Hydroxyproline (urine)
  30. Most common symptom of paget
  31. PAget disease of bone: dx
    clinical/radiographic features with supportive lab findings
  32. Paget disease of bone - txn
    No cure, but can be controlled by calcitonin or bisphosphonates
  33. Parathyroid Hormone (PTH) - physiology
    Parathyroid gland

    PTH regulates calcium homeostasis

    • Target organs
    • –Bone: calcium mobilization from bone
    • •Indirectly enhance bone resorption and release of calcium from bone
    • surfaces by activation of osteoclasts
    • •Osteoclasts do not have PTH receptors

    • –Kidney: reabsorption of calcium by renal tubules
    • •Potentiates by Vitamin D

    •Feedback mechanism: regulated by serum calcium level
  34. True or false: PTH act on osteoclast receptor
  35. Primary hyperPTdism
    tumor or hyperplasia --> inc serum Ca2+
  36. Secondary hyperPThism
    from kidney failure --> lower Ca2+ serum --> inc PTH --> act on bone but not kidney 

    cause by renal osteodystrophy (bone change secondary to kidney failure)
  37. Hyperparathyroidism - clinical presennation
    bone resorption
  38. hyperPTdism - radiograph
    Ground glass

    Cystic (Osteitis fibrosa cystica: brown tumor)
  39. hyperPTdism - histology
    characterized by the presence of multinucleated giant cells, which are osteoclasts (they are also present in “giant cell tumor of bone”)
  40. hyperPtdism - dx
    Laboratory findings of PTH and calcium
  41. hyperptdism - tx
    treat the underlying disease
  42. Vitamin D - physiology
    source: diet and skin 

    Activated in Kidney (beware of kidney-failed pt)

    active form inc absorption of Ca in intestine --> bone mineralization
  43. Vitamin D deficiency
    poorly mineralized bone matrix, susceptible to fracture

    In closed growth plate status: adult --> osetomalacia 

    • in open growth plate status: children --> ricket:
    • Excessive amount of cartilage and osteoid, poorly mineralized bone
    • §Growth retardation
    • §Skeletal deformity
  44. Bone Fracture - cause
    –High impact or stress

    –Pathologic fracture: Seen in medical conditions that weaken the bones, can be caused by trivial force
  45. Bone fracture: close
    skin is intact
  46. Bone fracture: compound/open
    skin is not intact, 

    bone is exposed and infection
  47. bone fracture: compression
    a collapse of a vertebra