MSK II Midterm > Bone pathology > Flashcards

Bone pathology Flashcards

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1
Q

What kinds of bones develop from intramembranous ossification?

A
  • flat bones: formation of bone without a preexisting cartilage matrix
  • the others do endochondral ossification… mostly long bones
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2
Q

If someone has short thumb and big toe, what gene is messed up?

A

-HOXD13

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3
Q

What is cleidocranial dysplasia?

A
  • LOF mutation in RUNX2

- patent fontanelles

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4
Q

Achondroplasia

A
  • impaired cartilage proliferation in the growth plate
  • common cause of dwarfism
  • short extremities
  • intramembranous bone not affected
  • mental function, life span, and fertility are not affected
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5
Q

mutation in achondroplasia

A
  • activating mutation in FGFR3
  • overexpression inhibits growth
  • most mutations are sporadic
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6
Q

Thanatophoric dysplasia

A
  • mot sommon lethal form of dwarfism
  • bell shaped abdomen
  • shorened limbs, frontal bossing, macrocephaly…
  • die at birth or soon after
  • also GOF FGFR3 mutation, but different from achondroplasia
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7
Q

Osteogenesis Imperfecta

A
  • congenital defect of bone fomration resulting in structurally weak bone
  • Auto dominant defect in Collagen type 1 synth
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8
Q

Clinical features of OI?

A
  • multiple fractures of bone
  • blue sclera: thinning of scleral collagen reveals underlying choroidal veins
  • hearing loss: bones in the middle ear easily fracture
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9
Q

Gene defect in OI

A

-COL1A1 or 2

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10
Q

Which subtype of OI is especially lethal?

A
  • type 2

- that is the only predominantly auto recessive one, the other 3 are dominant

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11
Q

Osteopetrosis

A
  • inherited defect of bone resorption resulting in abnormally thick, heavy bone that fractures easily
  • due to poor osteoclast function
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12
Q

mutation of what enzyme is in osteopetrosis?

A
  • carbonic anhydrase 2 (makes carbonic acid from H20 and CO2)
  • loss of acidic environment needed for bone resorption
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13
Q

clinical features of osteopetrosis

A
  • bone fractures
  • pancytopenia… bony replacement of the marrow (myelophthisic process)
  • vision and hearing impairment.. impinges CN’s
  • renal tubular acidosis: we can’t reabsorbe bicarb now… metabolic acidosis
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14
Q

Tx for osteopetrosis

A
  • bone marrow transplant!

- osteoclasts are derived from monocytes

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15
Q

another name for osteopetrosis

A

-alber-schonberg disease

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16
Q

What big morphology buzzword is for osteopetrosis

A

-erlenmeyer flask

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17
Q

Genetic defect for osteopetrosis

A
  • auto dominant: LRP5… hearing loss

- Infantile form: RANKL (auto recessive)

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18
Q

Mucopolysaccharaidoses

A
  • they accumulate inside chondrocytes… apoptosis

- abnormalities in hyaline cartilage

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19
Q

difference between osteopenia nad osteoporosis?

A
  • osteoporosis is bone mass 2.5 sd’s lower than mean peak bone mass
  • oseopenia is 1-2.5
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20
Q

most common forms of osteoporosis?

A

-senile and postmenopausal forms

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21
Q

What is osteoporosis

A
  • reduction in trabecular bone mass
  • results in porous bone with an increased risk for fracture
  • risk of oseoporosis is based on peak bone mass and rate of bone loss that follows after
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22
Q

clinical features of osteoporosis

A
  • bone pain and fractures in weight-bearing areas like the vertebrae, hip, and distal radius
  • bone density is measured using a DEXA scan
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23
Q

How are the serum calcium, phosphate, pth, and alk phos levels in osteoporosis?

A
  • NORMAL

- this helps to exclude osteomalacia which is nice because it’s like the same presentation

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24
Q

Tx of osteoporosis

A
  • exercise, vti D, and Ca2+
  • Bisphosphonates: induce apoptosis of oseoclasts
  • Estrogen replacement therapy is debated
  • glucocorticoids are contraindicated (worsen osteoporosis)
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25
gene defect for osteoporosis-pseudoglioma syndrome?
- LRP5 | - infant onset loss of vision, skeletal fragility
26
gene defect for osteopetrosis with renal tubular acidosis
-CA2
27
gene defect for osteopetrosis, late onset type 2?
- CLCN7 | - chloride channel, increased bone density, fragility
28
What are the top genetic factors for osteoporosis?
-RANKL, OPG, and RANK
29
hallmoar of osteoporosis?
-histologically normal bone that is decreased in quantity
30
where in the body will we see the effects of postmenopausal osteoporosis the most?
-vertebral bodies or bones that have a lot of surface area
31
is measurement of blood levels of Ca2+, Phosphorous, and alk phos diagnostic for osteoporosis?
- no! | - remember those labs are normal
32
Paget Disease (osteitis deformans)
-imbalance betwen osteoclast and osteoblast function -late adulthood... old ppl -localized process involve one or more bones: DOES NOT INVOLVE THE ENTIRE SKELETON -
33
What gene involvement is shared between OI and dermatofibrosarcoma protuberans?
- COL1A1 | - remember in the derm one, it's a translocation between COL1A1 and PDGFB
34
What are the 3 stages of paget disease of bone?
- osteoclastic - mixed osteoblastic-clastic - osteoblastic
35
What is the end result of paget disease
- thick, sclerotic bone that fractures easily | - biopsy reaveal a MOSAIC pattern of lamellar bone
36
Clinical features of paget diseas
- bone pain: microfractures - increasing hat size: skull is commonly affected - hearing loss: impinging CN's - lion-like facies: involvement of craniofacial bones - isolated elevated alk phos
37
What is the most common cause of isolated elevated alk phos in patients >40 y/o?
-Paget disease of bone
38
Tx of paget disease
- calcitonin: inhibits osteoclast function | - disphosphonates: induces apoptosis of osteoclasts
39
Complications of Paget disease
- high-output cardiac failure: due to formation of AV shunts in bone - osteosarcoma
40
gene mutation for paget disease
- SQSTM1 gene | - increased activity of NFKB....increases osteoclast activity
41
how will the osteoclasts look in paget disease?
- abnormally large | - more than normal 10 to 12 nuclei, sometime 100!
42
What region of the body is involved with paget disease?
- axial skeleton or prox femur | - can have leontiasis ossea (lion face)
43
How will the femurs look in pagets disease?
-weight bearing causes anterior bowing of the femurs
44
How will the skin look and feel in pagets?
-warms overlying skin bc hypervascularity
45
labs for someone with pagets?
- elevated serum alk phos | - normal serum Ca2+ and phosphorous
46
Ricketts
- defective mineralization of osteoid - low vit D... leads to low Ca and P - this one is with children - pigeon breast deformity - fronal bossing - rachitic rosary - bowing of the legs
47
what is the common theme is ricketts problems?
-deposition of osteoid in places
48
Osteomalacia
- low Vit d in Adults | - bad mineralization... weak bone... increased risk for fracture
49
lab findings for osteomalacia
- low Ca2 - low P - high PTH - high alk phos: happens when there is osteoblasts activated
50
If we have hyperparathyroidism, what three skeletal abnormalities will be there?
- osteoporosis: more severe in phalanges, vertebrae, and proximal femur - brown tumors: vascularity, hemorrhage, and hemosiderin - osteitis fibrosa cystica
51
What does BMP-7 induce?
- osteoblast differentiation | - secreted by kidneys
52
FGF-23
- made by osteocytes | - acts on kidney to regulate phosphate homeostasis and vit D production (dependent on Klotho)
53
simple fracture
-skin is intact
54
compund
-bone communicates with the skin
55
comminuted
-bone is fragmented
56
displaced
-ends of the bone at the fracture site are not aligned
57
stress
-slowly developing fracture that follows a period of increased physical activity in which the bone is subjected to repetitive loads
58
greenstick fracture
-extending only partially through the bone, common in infants when bones are soft
59
pathologic fracture
-involves bone weakened by an underlying disease process, such as a tumor
60
is the cortex normally affected by avascular necrosis?
- no | - the trabecular bone and marrow are though
61
Osteomyelitis
- infection of marrow and bone - usually in children - bacterial usually, arises via hematogenous spread - transient bacteremia seeds metaphysis (children) - open wound bacteremia seeds epiphysis (adults)
62
causes of osteomyelitis
- Staph aureus... most common - N gonorrhoea: sex ppl - salmonella: sickle cell - pseudomonas: Diabetic or IV drug abusers - pasteurella: dog or cat bite - Mycobacterium tuberculosis: usually involves vertebrae (pott disease)
63
clinical features of osteomyelitis
- bone pain with systemic signs of infection - lytic focus surrounded by sclerosis of bone on x ray, lytic focus is called sequestrum, and sclerosis is called involucrum
64
brodie abscess
-small IO abscess that frequently involves the cortex and is walled off by reactive bone
65
Sclerosing osteomyelitis of Garre
- jaw | - extensive new bone formation that obscures much of the underlying osseous structure
66
How is the diagnosis of osteomyelitis made?
-by blood culture
67
What will skeletal syphyllis look like?
- saber shins - see it on silver histochemical stains - gummas
68
Avascular septic necrosis
- ischemic necrosis of bone and marrow - causes include trauma or fracture, steroids, sickle cell anemia, and caisson disease - osteoarthritis and fracture are major complications`
69
Osteoid osteoma
-benign tumor of osteoblasts surrounded by a rim of reactive bone -young adults -cortex of long bones -
70
presentation of osteoid osteoma
- bone pain that RESOLVES WITH ASPIRIN - imagin: bony mass with a radiolucent core - appendicular skeleton
71
How is osteoid osteoma different from osteoblastoma?
-osteoblastoma is similar to this but it's larger (>2cm), arises in vertebra, and presents as bone pain that DOES NOT RESPOND TO ASPIRIN
72
What does the osteoid osteoma and osteoblastoma look like
-round to oval masses of hemorrhagic gritty tan tissue
73
Osteosarcoma
- Malignant proliferation of osteoblasts - teens - pathologic fracture or bone pain with swelling
74
Imaging for osteosarcoma
- sunburst | - codman triangle
75
risk factors for osteosarcoma
-familial retinoblastoma, paget disease, and radiation exposure
76
Where does osteosarcoma arise?
-in the metaphysis of long bones, usually the distal femure or proximal tibia (the knee!)
77
biopsy for osteosarcoma
-pleomorphic cells that produce osteoid
78
What genes will be mutated in osteosarcoma?
- RB: negative regulator of cell cycle - TP53 (li fraumeni) - INK4a (inactivated) - MDM2 and CDK3: inhibit p53 and RB function
79
what is diagnositc for osteosarcoma?
-formation of bone by tumor cells
80
What is an osteosarcoma called when malignant cartilage is abundant?
-chondroblastic osteosarcoma
81
Where does osteosarcoma like to spread to?
-the lungs! hematogenously
82
Morphology of osteosarcomas?
- bulky tumors that are gritty, gray-white | - remember that osteomas were gritty tan colored
83
outcome for osteosarcoma patients with metastases?
-poor
84
Osteochondroma
- tumor of bone with an overlying cartilage cap; most common benign tumor of bone - arises from a lateral projection of the growth plate (metaphysis); bone is continuous with the marrow space - overlying cartilage can transform (rarely) to chondrosarcoma
85
pathogenesis of osteochondroma
- reduced expressiong of EXT1 or EXT2 | - these genes encode enzymes that synthesize heparan sulfate glycosaminoglycans
86
What is another name for osteochondroma?
-exostosis
87
When do osteochondromas stop growing?
-at the time of growth plate closure... makes sense because it comes from the metaphysis
88
Chondroma
- benign tumor of cartilage | - usually arises in the medulla of small bones of the hands and feet
89
What 2 syndromes have multiple enchondromas?
- Maffucci syndrome and Ollier disease | - Maffucci also has spindle cell hemangiomas
90
pathogenesis of chondromas
- heterozygous mutations in the IDH1 and IDH2 genes - encode 2 isoforms of isocitrate dehydrogenase... leads to synth of 2-hydroxyglutarate - that is an oncometabolite... interferes with regulation of DNA methylation
91
If someone has maffucci syndrome, what else are they at risk for?
-other types of malignancies like ovarian carcinomas and brain gliomas
92
Chondrosarcoma
- malignant cartilage-forming tumor | - arises in medulla of the pelvis or central skeleton
93
What is special about the clear cell variant of chondrosarcoma?
-it originates in the epiphyses of long tubular bones
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What is a dedifferentiated chondrosarcoma
-low grade chondrosarcoma with a second, high grade component that does not produce cartilage
95
presentation of chondrosarcomas
-painful, progressively enlarging masses
96
where do chondrosarcomas spread to?
-hematogenously to the lungs
97
Ewing sarcoma
- malignant proliferation of poorly-differentiated cells derived from neuroectoderm - arises in the diaphysis of long bones; usually in male children - onion skin appearance on x ray
98
what will biopsy show us for ewing sarcoma?
- small, round blue cells that resemble lymphocytes | - can be confused with lymphoma or chronic osteomyelitis
99
What is the characteristic tranlocation for ewing sarcoma?
- 11,22 | - EWS (22) and FLI1 (11) genes
100
How does ewing sarcoma often present?
- with mets | - responsive to chemo
101
what gives us a clue that ewing sarcoma has a greater degree of neuroectodermal differentiation?
-homer-wright rossettes
102
What is an important prognostic finding for ewing sarcomas?
-the amount of chemo induced necrosis
103
Giant cell tumor
- comprised of multinucleated giant cells and stomal cells - occurs in young adults - arises in epiphysis of long bones, usually the distal femur or prox tibia (knee) - soap bubble appearance on x ray - locally aggressive, may recur
104
what is a synonym for giant cell tumor?
- osteoclastoma | - often destroy the overlying cortex
105
morphology for giant cell tumor
- sheets of uniform oval mononuclear cells and numerous osteoclast-type giant cells - the tumor cells do not synthesize bone or cartilage, but reactive bone may be present at the periphery
106
anuerysmal bone cyst (ABC)
- tumor characterized by multiloculated blood-filled cystic spaces - eccentric, expansile lesion with well-defined margins
107
pathogenesis of ABC
- rearrangements of chormosome 17p13 - results in fusion of coding region of USP6 to promoters of genes that are highly expressed in osteoblasts... leads to USP6 overexpression
108
What is USP67
- encodes ubiquitin specific protease... regulates activity NFKB - so a lot of NFKB floating around - that upregulates metalloproteases that lead to cystic resorption of bone
109
morphology of ABC
-multiple blood filled cystic spaces separated by thing, tan-white septa
110
What is fibrous dysplasia?
-all components of normal bone are present, but they do not differentiate into mature structures
111
What is Mazabraud syndrome
- fibrous dysplasia | - soft tissue myxomas
112
McCune -Albright syndrome
-polyostotic disease with cafe-au-lait skin pigmentations and endocrine abnormalities, especially precocious puberty
113
what is the mutation for fibrous dysplasia?
- GOF in GNAS1 - also mutated in pituitary adenomas - make a constitutively active Gs ptn
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