Bone Pathology - Robbins

Front 1

Bone is what type of tissue?

Back 1

Connective tissue

Front 2

Main inorganic component of bone

Back 2

calcium hydroxyapatite

Front 3

2 functions of calcium hydroxyapatite in bone

Back 3

gives bone strength and hardness

stores:
- calcium
- phosphorus
- sodium
- magnesium

Front 4

What proportion of the following minerals in a healthy human are found in the bone?

Calcium:
Phosphorus:
Sodium:
Magnesium:

Back 4

Calcium: 95%
Phosphorus: 85%
Sodium: 65%
Magnesium 65%

Front 5

Osteoid

Back 5

unmineralized bone

Front 6

Organic components of bone

Back 6

cells
matrix proteins

Front 7

3 types of bone-forming cells

Back 7

osteoprogenitor cells
osteoblasts
osteocytes

Front 8

Osteoprogenitor cells

what:
where:
why:

Back 8

Osteoprogenitor cells:

what: pluripotent mesenchymal stem cells

where: vicinity of all bony surfaces

why: produce osteoblast cell lineage

Front 9

2 factors important in the differentiation of osteoblasts

Back 9

BMPs - stimulate osteoprogenitor cells to produce offspring

TF core binding factor a1 - osteoblastic differentiation

Front 10

Where are osteoblasts located?

Back 10

surface of bone

Front 11

3 functions of osteoblasts

Back 11

- synthesize, transport, arrange matrix proteins
- initiate mineralization
- express hormone binding cell-surface receptors (CSRs)

Front 12

What binds hormone binding CSRs on osteoblasts?

Back 12

PTH
vit. D
estrogen
cytokines
growth factor
ECM proteins

Front 13

2 molecules involved in lipid metabolism recently found to influence osteoblast activity

Back 13

leptin
LDL receptor-related protein 5

Front 14

life span of metabolically active osteoblasts

Back 14

3 months

Front 15

3 fates of osteoblasts

Back 15

apoptosis
quiescent, flattened, bone surface lining cells
osteocytes surrounded by matrix

Front 16

How do osteocytes communicate?

Back 16

cell processes traverse caniculi
contacts along gap junctions allow travel of surface membrane potentials and substrates

Front 17

Osteocytes are important in the homeostatic control of what?

Mechanism?

Back 17

Osteocytes help control serum levels of calcium and phosphorus
by altering their concentrations in the local ECM compartment

Front 18

Osteocytes can do what with the mechanical forces they detect?

Back 18

translate mechanical forces into biological activity

Front 19

Which bone-forming cell is the most numerous?

Back 19

osteocytes

Front 20

Function of osteoclasts

Back 20

bone resorption

Front 21

Osteoclasts are derived from which cell lineage

Back 21

hematopoietic progenitor cells that give rise to monocytes & macrophages

Front 22

Member of TNF superfamily involved in osteoclast function

Back 22

RANK

Front 23

Where is RANKL expressed?

Back 23

membrane of osteoclasts

Front 24

What does RANK-RANKL binding signal?

Back 24

Onset of osteoclastogenesis

Front 25

Function of osteoprotegrin (OPG)

Back 25

competitively inhibits RANK-RANKL binding

Front 26

mature multinucleated osteoclasts

Back 26

fusion of circulating mononuclear precursors
limited life span - 2 weeks

Front 27

Howship lacunae

Back 27

scalloped resorption pits produced by mature osteoclasts

ruffled border – part of osteoclast mb w/ many villi overlying pit
mb bordering this region forms seal w/ underlying bone

Front 28

What occurs within Howship lacunae?

Back 28

osteoclast acidifies bone w/ H+ pump system
digestive enzymes, eg: collagenase, disassemble matrix prtns
elemental units recycled for bone renewal

Front 29

2 types of bone proteins

Back 29

Collagen type I
noncollagenous proteins derived from osteoblasts

Front 30

Backbone of bone matrix

Back 30

type I collagen

Front 31

collagen deposited by osteoblasts in what 2 patterns?

Back 31

woven bone (random weave)
lamellar bone (orderly, layered pattern)

Front 32

where is woven bone found?

Back 32

in fetal skeleton
at growth plates
in pathological lesions of adults (e.g.: fx sites)

Front 33

4 types of lamellar bone

Back 33

3 in cortex:
- circumferential
- concentric
- interstitial
trabecular lamellae (parallel to long axis)

Front 34

noncollagenous proteins of bone are bound to _____

Back 34

matrix

Front 35

4 functional groups of noncollagenous proteins in bone

Back 35

adhesion
Ca2+ binding
mineralization
enzymes, hormones, growth factors

Front 36

only noncollagenous protein unique to bone

Back 36

osteocalcin

Front 37

Osteocalcin is a specific and sensitive marker of ____?

Back 37

osteoblastic activity

Front 38

BMU

Back 38

basic multicellular unit
functional unit of bone
osteoblasts & osteoclasts coordinating

Front 39

how much of skeleton is replaced annually?

Back 39

10%

Front 40

5 bone growth factors

Back 40

bone morphogenic proteins (BMPs)
fibroblast growth factor (FGF)
platelet-derived growth factor (PDGF)
insulin-like growth factor
transforming growth factor-β (TGF-β)

Front 41

skeletal morphology encoded by what type of gene?

Back 41

Homeobox

Front 42

In what week of gestation does enchondral ossification begin?

Back 42

8th week

Front 43

physis

Back 43

aka: growth plate
plate of cartilage model trapped btw expanding centers of ossification

Front 44

appositional growth

Back 44

deposition of new bone on preexisting surface

Front 45

2 regulators of bone growth, especially at physis

Back 45

Indian hedgehog gene
PTH-related protein (PTHRP)

Front 46

Dysostoses

Back 46

developmental anomalies from local problems in migration of mesenchymal cells

Front 47

Dysplasias

Back 47

mutations in regulators of skeletal organogenesis affect cartilage & bone globally

Front 48

most common disease of physis

Back 48

achondroplasia

Front 49

Achondroplasia

Back 49

most common cause of nonlethal dwarfism
caused by defect in paracrine cell signaling --> reduced chondrocyte prolifereation

Front 50

Genetics of achondroplasia

Back 50

point mutation (Arg for Gly375) in FGF receptor 3 gene
-- on chromosome 4p
-- FGFR3 inhibits cartilage proliferation
-- causes FGFR3 to be constantly activated, suppressing growth
-- AD transmission
-- 80% cases spontaneous mutation

Front 51

Achondroplasia: clinical picture

Back 51

- shortened proximal extremities
- trunk relatively normal length
- enlarged head w/ bulging forehead & depression of root of nose
- not assoc. w/ Δ longevity, intelligence, reproductive status

Front 52

most common type of lethal dwarfism

Back 52

Thanatophoric dwarfism

Front 53

Thanatophoric dwarfism

etiology
fatality

Back 53

mutation of FGFR3 --> much more severe phenotype

death by resp. insufficiency 2° underdeveloped thoracic cavity

Front 54

Osteogenesis imperfecta

Back 54

group of type I collagen disorders
aka: brittle bone disease

Front 55

structures affected in osteogenesis imperfecta

Back 55

significant skeletal involvement
also: joints, eyes, ears, skin, teeth

Front 56

Osteogenesis imperfecta

pattern of inheritance
genes affected

Back 56

AD inheritance
genes coding for a1 & a2 chains of collagen polypeptide

Front 57

2 types of mutations leading to osteogenesis imperfecta

Back 57

mutations yielding qualitatively normal collagen (but less of it) give rise to mild to moderate phenotypes

mutations yielding abnormal collagen give rise to severe and lethal phenotypes

Front 58

morphological definition of all types Osteogenesis imperfecta

Back 58

too little collagen:
- extreme skeletal fragility
- type of osteoporosis
- marked cortical thinning
- attenuation of trabeculae

Front 59

Type I Osteogenesis Imperfecta

Back 59

- normal life span
- increased number fractures in childhood (decr. post puberty)
- usu. acquired, not inherited
- blue sclerae, allow part visualization underlying choroid
- hearing loss
--- sesnroineural deficit
--- abnormal mechanical condxn
- dental imperfections
--- small, misshapen, blue-yellow teeth
--- 2° decreased dentin

Front 60

Type II Osteogenesis Imperfecta

Back 60

- uniformly fatal in utero or perinatally
- extraordinary bone fragility w/ multiple fractures in utero

Front 61

Mucopolysaccharidoses

Back 61

group of lysosomal storage diseases

- caused by deficiencies in enzymes that degrade dermatan, herpan & keratan sulfates
- implicated enzymes mainly acid hydrolases
- mesenchymal cells, esp. chondrocytes, particularly affected
- abnormalities in hyaline cartilage -->
--- short stature
--- chest wall abnormalities
--- malformed bones

Front 62

Osteopetrosis

Back 62

group of rare, genetic disorders
decreased osteoclast bone resorption
diffuse, symmetrical skeletal sclerosis

Front 63

Osteoporosis

Back 63

increased bone porosity from reduced bone mass

- changes predispose bone to fx
- may be localized to certain bone or region, e.g.: disuse osteoporosis of a limb
- may involve entire skeleton – metabolic bone ds

Front 64

4 factors of aging that contribute to senile osteoporosis

Back 64

- decreased replicative actiivty of osteoprogenitor cells
- decreased synthetic activity of osteoblasts
- decreased biological actiivty of matrix-bound growth factors
- reduced physical acitivty

Front 65

4 factors that contribute to post-menopausal osteoporosis

Back 65

- decreased serum estrogen
- increased IL-1, IL-6, TNF levels
- increased expression of RANK, RANKL
- increased osteoclast activity

Front 66

3 overall factors contributing to senile and post-menopausal osteoporosis

Back 66

genetic factors
physical activity
nutrition

Front 67

Paget's disease, aka:

Back 67

osteitis deformans

Front 68

3 stages of Paget's disease

net effect:

Back 68

(1) initial osteolytic stage
(2) mixed osteolytic-osteoblastic stage, ending with osteoblastic predominance
(3) burnt-out quiescent osteosclerotic stage

net effect: gain of bone mass

Front 69

Epidemiology of Paget's disease

Back 69

usually occurs in mid-adulthood
relatively common in Whites from W. Europe

Front 70

Clinical features of Paget's disease

Back 70

most affected individuals are asymptomatic

clinical course extremely variable
- axial skeleton or proximal femur involved in up to 80% cases
- enlarged calvarium
- involvement of ribs, fibula, small bones of hands/feet unusual
- pain most common prob - 2° comb. μfx & bone overgrowth compressing nn roots
- variety of tumor & tumor-like conditions develop in pagetic bone

Front 71

radiographic characteristics of Paget's disease

Back 71

radiography frequently diagnostic

Pagetic bone typically enlarged w/ thick, coarsened cortices & cancellous bone

Front 72

biochemical abnormalities associated with Paget's disease

Back 72

increased serum level of alkaline phosphatase

increased urinary excretion of hydroxyproline

Front 73

Hyperparathyroidism

Back 73

increased serum PTH causes hyperstimulation of osteoclast activity

unabated osteoclast bone resorption w/ entire skeleton affected

Front 74

Primary hyperparathyroidism

Back 74

autonomous hyperplasia or a tumor,
usu. adenoma, of parathyroid gland

Front 75

Secondary hyperparathyroidism

Back 75

prolonged states of hypercalcemia cause compensatory hypersecretion of PTH

Front 76

osteitis fibrosa cystica

Back 76

anatomic changes of severe, late-stage hyperparathyroidism

rarely seen in industrialized countries

Front 77

Which form of hyperparathyroidism is usually more severe and prolonged?

Back 77

primary

Front 78

Classifications of fractures
closed -
compound -
communited -
displaced -

Back 78

complete vs. incomplete
closed (simple) – overlying tissue intact
compound – fx site communicates with the skin surfact
communited – bone is spintered
displaced – ends of bone at fx site not aligned

Front 79

Pathologic fracture

Back 79

occurs at a site already altered by disease process

Front 80

Stress fracture

Back 80

slowly developing fracture following a period of increased activity with new, repetitive loads on the bone

Front 81

Process of fracture repair

Back 81

fracture --> ruptured vessels --> hematoma
clotted blood --> fibrin mesh --> enclosed inflammatory site
PDGF, TGF-b, FBF activate osteoprogenitors, BMU

end week 1: procallus - fusiform, soft tissue, anchors fractured ends

osteoprogenitors deposit subperiosteal trabeculae of woven bone

end week 2/3 - repair tissue at maximum girth

last step: endochondral ossification of new cartilage

Front 82

Complications of fracture repair

Back 82

- deformities from displaced and -comminuted fx, esp. w/ inadequate immobilization
- infection in comminuted and open fx
- derailed bone repair 2° inadequate Ca2+, P, vit D; DM; sys. infxn; vasc. insufficieny

Front 83

All forms of osteonecrosis result from what process?

Back 83

ischemia

Front 84

6 mechanisms producing ischemia in bone

Back 84

- mechanical vascular interruption (fx)
- corticosteroids
- thrombosis & embolism (N bubbles in dysbarism)
- vessel injury 2° vasculitis, radiation therapy
- increased intraossesous pressure w/ vascular compression
- venous HTN

Front 85

Clinical course following subchondral infarcts in bone

Back 85

- chronic pain initially assoc. only w/ physical activity (then constant)
- subchondral infarcts often collapse
- may predispose to severe, 2° OA

Front 86

Clinical course following medullary infarcts in bone

Back 86

- clinically silent, exc. large ones (Gaucher ds, dysbarism, Hgbopathies)
- usu. remain stable over time
- rarely site of malignant transformation

Front 87

Degenerative joint disease, aka:

Back 87

osteoarthritis

Front 88

Osteoarthritis

Back 88

progressive degredation of articular cartilage
intrinsic disease involving mechanical and biochemical factors

Front 89

Risk of OA increases with increased _____

Back 89

bone density

Front 90

morphological characteristics of early OA

Back 90

degenerating cartilage contains
- increased water
- decreased proteoglycans

weakening of collagen network
- degradation of preexisting collagen

Front 91

chronic osteoarthritic cartilage has increased levels of what molecules?

Back 91

IL-1, TNF, NO (--> PCD)

Front 92

symptoms characteristic of OA

Back 92

- deep, achy pain, worse w/ use
- morning stiffness
- crepitus
- limited ROM

Front 93

joints characteristically involved in OA

Back 93

hips, knees, lumbar & cervical vertebrae
PIP, DIP, 1st CMC, 1st TMT joints

Front 94

Heberden nodes

Back 94

in fingers
characteristic in women, not men

prominent osteophytes in DIPs

Front 95

Rheumatoid arthritis

Back 95

- chronic, systemic inflammatory disorder
- principally attacks joints --> nonsuppurative, proliferative, inflammatory synovitis
- progresses to destruction of articular cartilage & ankylosis of the joints
- also affects skin, blood vessels, heart, lungs, muscles
- autoimmunity heavily involved

Front 96

morphology of RA joints

Back 96

Synovium
- edematous
- thickened
- hyperplastic
- bulbous fronds
-
Inflammatory cells
- densely perivascular
-. B cells, TH cells, Mφ

Increased vascularity
Hemosiderin deposits
Fibrin aggregation
PMNs in synovial fluid

Ostoclastic activity allows synovium to penetrate bone
--> juxta-articular erosisons, subchondral cysts, osteoporosis

pannus formation

Front 97

pannus

Back 97

mass of synovium & synovial stroma

consists of inflamm cells, granulation tissue, fibroblasts

grows over articular cartilage, causing its erosion

then bridges apposing bones --> fibrous ankylosis --> bony ankylosis

Front 98

skin involvement in RA

Back 98

rheumatoid nodules
- most common cutanous lesions in RA
- firm, nontender, round to oval
- arise in s.c. tissue
- central zone fibrinoid necrosis w/ prom. rim epithlioid histiocytes & many lymphocytes

Front 99

common vascular complications of RA

Back 99

vasculititides
obstruction of vasa nervorum
obstruction of digital arteries

Front 100

clinical course of RA

Back 100

- initial malaise, fatigue, generalized musculoskeletal pain
- followed by clear joint involvement
~10% pts have acute onset w/ polyarticular involvement developing rapidly
- usu. small joints affected first: MCP, DIP, PIP, MTP, IP
- then wrists, ankles, elbows, knees
- lumbosacral region usu. spared
- involved joints swollen, warm, painful, particularly stiff on rising or s/p inactivity
- large synovial cysts, e.g.Baker’s, may dev 2° ↑intra-articular P causing outpouchings synovium

Front 101

diagnostic criteria for RA

Back 101

- morning stiffness
- arthritis in 3 or more joints
- arthritis of typical hand joints
- symmetric arthritis
- rheumatoid nodules
- serum RF
- typical radiographic changes

Front 102

5 ways JA differs from RA

Back 102

- oligoarthritis more common
- systemic onset more frequent
- large joints affected more often than small joints
- rheumatoid nodules & RF usu. absent
- ANA seropositivity common

Front 103

commonly targeted joints in JA

Back 103

knees, wrists, elbows, ankles

warm, swollen, typical symmetric involvement

Front 104

describe systemic onset of JA

Back 104

may beg abruptly with...
- high spiking fever
- migratory & transient rash
- HSM
- serositis

Front 105

Seronegative spondyloarthritis

Back 105

immune-mediated, possibly by T cell response to unknown Ags

produce inflammatory peripheral or axial arthritis & inflammation of tendinous attachment

types: ankylosing spondylitis, reactive arthritis, psoriatic arthritis, arthritis assoc w/ IBD

Front 106

Ankylosing spondyloarthritism, aka:

Back 106

rheumatoid spondylitis, Marie-Strümpell disease

Front 107

end disease process of ankylosing spondyloarthritis in the spine

Back 107

- inflammation of tendinoligamentous insertion sites
- followed by ossification
- ossification forms osteophytes
- osteophytes create severe spinal immobility

Front 108

Joint involvement in ankylosing spondyloarthritis

Back 108

axial joints, especially sacroiliac joints

Front 109

when does ankylosing spondyloarthritis usually become symptomatic?

Back 109

teens to 20s

Front 110

is there an association between spondyloarthritis and HLA-B27?

Back 110

Yes - 90% pts are HLA-B27 positive, although some subtypes not associated with disease

Front 111

characterize ankylosing spondyloarthritis

Back 111

chronic synovitis with destruction of articular cartilage & bony ankylosis, esp SI & apophyseal joints

Front 112

Reactive arthritis

Back 112

an episode of noninfectious arthritis of the appendicular skeleton

occuring within one month of infection localized elsewhere

Front 113

Infections most commonly associated with reactive arthritis

Back 113

most infections are GUIs: Chlamydia

other common infections are GI: Shigella, Salmonella, Yersinia, Campylobacter

Front 114

Reiter's syndrome triad:

Back 114

arthritis
nongonococcal urethritis or cervicitis
conjunctivitis

Front 115

arthritic symptoms associated with reactive arthritis

Back 115

- joint pain & low back pain common early symptoms
- ankles, knees, feet affected most often
- usu. in asymmetric pattern
- sausage finger (synovitis of digital tendon sheath)
- calcaneal spurs & osteophytes
--- from ossification of tendoligamentous insertion sites

Front 116

Epidemiology of reactive arthritis

Back 116

Most patients in 20s, 30s
80% are positive for HLA-B27

Front 117

4 types of infectious arthritis

Back 117

Viral arthritis
Lyme arthritis
Tuberculous arthritis
Suppurative arthritis

Front 118

Suppurative arthritis
etiology -
presentation -
systemic effects -

Back 118

bacteria seed joint during episode bacteremia

most common bacteria:
- Staph, Strept, H. influenzae & G(-) bacilli

classic presentation:
sudden development of acutely painful, hot, swollen joint with restricted ROM

systemic findings of fever, ↑WBCs, ↑ESR

Front 119

endogenous crystals that cause pathology

Back 119

monosoidum urate,
calcium pyrophaophate dihydrate,
calcium phosphate

Front 120

exogenous crystals that cause pathology

Back 120

corticosteroid esters
talcum
polyethylene
mehtyl methacrylate

Front 121

what do pathogenic crystals do?

Back 121

trigger cascade that leads to cytokine-mediated cartilage destruction

Front 122

Gout

Back 122

transient attacks of acute arthritis initiated by crystalization of urates in/around joints

leads eventually to chronic gouty arthritis

tophi

Front 123

tophi

Back 123

deposition of urate masses in joints form large aggregates with surrounding inflammatory reaction

Front 124

most common visceral complication of chronic gout

Back 124

urate nephropathy

Front 125

uric acid is the end product of what metabolic pathway?

Back 125

purine metabolism

Front 126

key enzyme deficiency in gout

Back 126

HGPRT - involved in purine salvage pathway

deficiency causes
- decrease in salvage pathway
- increase in de novo pathway
- increased production uric acid

Front 127

Lesch-Nyhan Syndrome

Back 127

- rare, X-linked condition with complete absence of HGPRT

- only in males

- hyperuricemia, severe neruological deficits with mental retardation & self-mutilation

Front 128

factors contributing to conversion of asymptomatic hyperuricemia to primary gout

Back 128

- age
- genetic predisposition
- heavy alcohol consumption predisposes to gout attack
- obesity
- certain drugs, e.g.: thiazides
- lead toxicity predisposes to saturnine gout

Front 129

plasma level of uric acid considered elevated

Back 129

plasma level > 7 mg/dL

b/c saturates plasma at normal core body temperature and blood pH

Front 130

Why do urate crystals form in joints but not in blood vessels?

Back 130

synovial fluid is a poorer solvent for uric acid than is plasma

temperature at the small, distal joints can be as low as 20*C

Front 131

pathogenesis of gout attacks following urate crystal formation

Back 131

- some event (eg: trauma) initiates release of crystals into synovial fluid
- released crystals are chemotactic to WBCs & activate complement (yielding C3a, C5a)
- phagocytsosis of crystals causes release toxic ROS & LTB4
- activated PMNs & Mφ produce inflammatory cytokines
- acute arthritis eventually remits (days to weeks) even if untreated

Front 132

four stages of gout

Back 132

(1) asymptomatic hyperuricemia
(2) acute gouty arthritis
(3) intercritical gout
(4) chronic tophaceous gout

Front 133

length of time between first gout attack and development of chronic tophaceous gout

Back 133

average 12 years

Front 134

Pseudogout, aka:

Back 134

calcium pyrophosphate crystal deposition disease (CPPD)
or chondrocalcinosis

Front 135

epidemiology of pseudogout

Back 135

usually occurs in pts > 50 y/o
sexes & races equally affected

Front 136

3 types of pseudogout

Back 136

sporadic (idiopathic)
hereditary
secondary

Front 137

hereditary pseudogout

Back 137

crystals dev relatively early in life - associated with severe OA

AD form related to ANKH gene mutation

ANKH: transmembrane inorganic pyrophosphate transport channel

Front 138

secondary pseudogout

Back 138

associated with various disorders:
- previous joint damage
- hyperparathyroidism
- hemochromatosis
- hypomagnesemia
- hypothyroidism
- ochronosis
- DM

Front 139

pathogenesis of pseudogout

Back 139

crystals develop in articular matrix, menisci, intervertebral discs

may rupture & seed joint upon enlargement

upon release into joint, elicit IL-8 production
inflammatory infiltrate rich in PMNs

Front 140

morphology of pseudogout crystals

Back 140

- chalky white friable deposits
- oval, blue-purple aggregates
- individual xstals 0.5 to 5μm
- geometrically shaped

Front 141

Osteochondroma

Back 141

benign, cartilage capped outgrowth attached to skeleton by bony stalk

inactivation both copies of EXT gene in physis chondrocytes (sporadic & hereditary)

occur in bones of endochondral origin

arise in metaphysis near physis of long tubular bones, esp. near knee

Front 142

Epidemiology of osteochondroma

Back 142

solitary osteochondromas – late adolescence/early adulthood

multiples – usu. hereditary (AD) - childhood

men > women

Front 143

Chondroma

Back 143

benign tumors of hyaline cartilage

Front 144

endochondromas

Back 144

chondromas originating in medullary cavity

Front 145

subperiosteal chondromas

Back 145

chondromas originating on surface of bone

Front 146

Ollier disease

Back 146

multiple endochondromas

Front 147

Maffucci syndrome

Back 147

multiple endochondromas associated w/ soft tissue hemangiomas

Front 148

characteristic radiographic features of chondromas

Back 148

unmineralized nodules of cartilage

O ring sign: well-circumsribed oval lucencies surrounded by thin rim radiodense bone

Front 149

Chondroblastoma

Back 149

rare benign tumor
usually near knee, epiphyses/apophyses
usu. painful

rad: well-defined geographic lucency w/ spotty calcifications

Front 150

chondrosarcomas - common feature

Back 150

production of neoplastic cartilage

Front 151

Characteristics of chondrosarcomas

Back 151

usu. 40 y/o+
usu. in central portions of skeleton: pelvis, shoulder, ribs
painful, progressively enlarging masses
rad: prominent endosteal scalloping

Front 152

Fibrous cortical defect & nonossifying fibroma

Back 152

Fibrous cortical defect & nonossifying fibroma

- very common: 30-50% kids > 2 y/o
- DEVELOPMENTAL DEFECTS, not neoplasms
- arise eccentrically in metaphysis of distal femur & proximal tibia
- large defects yield nonossifying fibromas
- radiography: elongated, sharply demarcated radiolucencies surry by thin zone of sclerosis
- asymptomatic: limited growth φ & spontaneously resolve w/ replacement by normal bone

Front 153

Fibrous dysplasias (general)

Back 153

benign tumor ~ localized developmental arrest

all components normal bone present, but do not differentiate into mature structures

Front 154

monostotic firbrous dysplasia

Back 154

70% all cases, usu. in early teens & stops growing at time of physis closure
ribs, femur, tibia, jawbones, calvaria, humerus
asymptomatic
can cause marked enlargement & distortion of bone

Front 155

polyostotic fibrous dysplasia without endocrine dysfunction

Back 155

- 27% all cases, manifests earlier than monostotic & con’t causing probs into adulthd
- femur, calvaria, tibia, humerus, ribs, fibula, radius, ulna, mandible, vertebrae
- craniofacial involvment in 50% pts
- propensity shoulder & pelvic girdle involvement  severe, crippling deformities
- spontaneous, often recurrent, fx

Front 156

McCune-Albright Syndrome

Back 156

polyostotic fibrous dysplasia w/ café au lait skin pigmentation & endocrinopathies

sexual precocity, hyperthyroid, pit. adenomas secrete GH, 1° adrenal hyperplasia

radiographic: ground-glass appearance & well-defined margins

Front 157

Fibrosarcoma & Malignant fibrous histiocytoma

Back 157

- fibroblastic collagen-producing sarcomas of bone
- usu affect middle-aged to elderly
- usu arise de novo
- large, hemorrhagic, tan-white masses
- destroy underlying bone & freq. ext. into soft tissues
- enlarging, painful masses arising in metaphyses of long bones & pelvic flat bones
- propensity to pathologic fx

Front 158

Ewing & PNET

Back 158

- malignant small round cell tumors of bone & soft tissue

Ewing – youngest age presentation of all bone sarcomas

- diaphyses of long tubular bones, esp. femur & flat bones of pelvis

painful, enlarging masses

affected site tender, warm, swollen

xrays: destructive lytic tumor w/ permeative margins & ext. into soft tissues

characteristic periosteal reactions --> layers reactive bone in onionskin pattern

Front 159

Giant Cell Tumor

Back 159

profusion of multinucleated osteoclast-type giant cells (aka: osteoclastoma)

in adults: epiphyses & metaphyses
in teens: confined by physis & limited to metaphysis

arise around knee – often causes arthritic symptoms

rad: large, purely lytic, eccentric, erode into subchondral bone plate

Front 160

most common form of skeletal malignancy

Back 160

metastatic bone tumors

Front 161

modes of spread to bone metastases

Back 161

direct extension
lymphatic or hematogenous dissemination
intraspinal seeding (Batson plexus of veins)

Front 162

most metastatic bone tumors involve which bones?

Back 162

most involve axial skeleton, prox. femur, humerus
(rich capillary network, slow blood flow, nutrient environment)

Front 163

mode by which bone metastases cause bone resorption

Back 163

metastatic cells produce PGs, IL, PTHRP
-- signal osteoclastic bone resorption
-- tumor cells themselves do not resorb bone

most elicit mixed lytic & blastic reaction

Front 164

What does increased urinary excretion of hydroxyproline indicate?

Back 164

increased collagen breakdown