R/O - Pathology of bone disorders Flashcards

1
Q

unmineralized bone is called:

A

osteoid

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2
Q

osteoblasts secrete what growth factors?

A
  • IL-1

- RANKL (receptor activator of NFkB which combines with RANK receptor on osteoclasts

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3
Q

what cells live in howship lacunae?

A

osteoclasts

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4
Q

osteoclasts are derived from what lineage?

A

hematopoietic progenitor cells

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5
Q

what type of bone?

  • normally present in fetal skeleton, growth plates, and processes where there is very rapid bone production
  • almost always pathologic in adults
A

woven

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6
Q

what are the 4 types of lamellar bone?

A
  • concentric
  • interstitial
  • inner circumferential
  • outer circumferential
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7
Q

what are the 3 developmental disorders of bone pathology?

A
  • achondroplasia
  • osteogenesis imperfecta
  • osteopetrosis
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8
Q

what is the pathology of achondroplasia?

A
  • point mutation in gene encoding for FGFR3

- FGFR is persistently activated - inhibition of normal proliferation of chondrocytes at growth plates

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9
Q

what is the inheritance of achondroplasia?

A

AD

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10
Q

premature sealing of growth plates - diagnosis?

A

achondroplasia

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11
Q

what cell type is proliferating in the zone of proliferation?

A

chondrocytes

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12
Q

what is the pathology of osteogenesis imperfecta?

A
  • abnormalities of type 1 collagen synthesis

- mutations in genes that code for a1 an a2 chains

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13
Q

what is the inheritance of osteogenesis imperfecta?

A

AD

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14
Q

what are the 4 main types of osteogenesis imperfecta?

A
  • type I: increased fracture risk, not deforming
  • type II: lethal, multiple fractures in utero
  • type III / type IV: progressive deformity
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15
Q

what is the morphology seen in OI?

A
  • decreased bone thickness because of sluggish periosteal bone formation
  • reduced number of trabeculae
  • abnormally thin trabeculae
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16
Q

osteopetrosis is due to defective activity of what cell type?

A

osteoclasts

17
Q

what is the pathology of osteopetrosis?

A
  • decreased osteoclastic bone resorption

- diffuse skeletal sclerosis

18
Q

what is the inheritance of osteopetrosis?

A
  • AR: malignant

- AD: benign (normal life span)

19
Q

what is the clinical picture of osteopetrosis?

A
  • increased incidence of fracture (more brittle)
  • anemia
  • thrombocytopenia
  • increased susceptibility to infections (less marrow space)
  • possible cranial nerve palsies
20
Q

what parts of bone are thinned in osteroporosis?

A

cortex and trabeculae

21
Q

what are the primary causes of osteoporosis?

A
  • age

- menopause

22
Q

what is the best imaging modality for osteoporosis? why?

A

DEXA - identifies quantitative loss of bone

23
Q

how does estrogen increase bone formation?**

A
  • increases collagen synthesis by osteoblasts

- prevents bone resporption by inhibiting osteoclast differentiation (osteoprotegerin)

24
Q

how does decreased estrogen (menopause) lead to decreased bone density?**

A

regulation of osteoclast activity:

  • increased secretion of IL-1, IL-6, TNF, leading to increased RANK which stimulates osteoclasts
  • decreased levels of osteoprotegerin (OPG), which is protective of bone
25
how does glucocorticoid excess affect osteoclast metabolism?
increase in: - osteoclast survival - cancellous osteoclasts - bone resorption
26
how does glucocorticoid excess affect osteocyte metabolism?
- increased apoptosis - decreased canalicular circulation - decreased bone quality
27
how does glucocorticoid excess affect osteoblast metabolism?
- decreased osteoblastogenesis - increased apoptosis - early and continual decrease in cancellous osteoblasts, synthetic ability, bone formation
28
- generalized pain - fractures - mottled areas of lucency ("pseudofractures")
osteomalacia
29
- skeletal deformities - loss of rigidity - bowing of the legs - enlarged costochondral junctions - pigeon breast deformity - kyphosis - frontal bossing
rickets
30
osteomalacia is characterized by:
abnormally high ratio of osteoid to mineralized bone