Walby-Musculoskeletal Flashcards
What is the role of the 206 bones in the human body?
Hematopoiesis Mineral homeostasis (Ca++, Phos) Mechanical support, protection of internal organs
What % of bone is inorganic, organic?
35% organic
65% inorganic
What is the main inorganic component of bone? What is its fcn? What other inorganic minerals are stored in bone?
calcium hydroxyapatite
gives bone its hardness
calcium, phosphorus, sodium, magnesium
What is osteoid?
unmineralized bone
What are osteoprogenitor cells? Where are they located?
pluripotential mesenchymal cells
**lie near & on bony surfaces
Where are osteoblasts located? WHat is one of their special functions?
on the surface of bones
**start mineralization
BUILD BONE
Where are osteoclasts located? What are they derived from?
come from: granulocyte-monocyte precursors in bone marrow
Location: Howship’s lacunae
**note; these guys are multinucleated!!
What is the function of osteocytes? How do they communicate b/w one another?
role in calcium & phosphorus homeostasis
**communicate via canaliculi
located in lacunae
From inside to outside...list the locations of the following cell types in the bone... Osteogenic Cell Osteoclast Osteoblast Osteocyte
Inside: Osteoclast Osteocyte Osteoblast Osteogenic Cell Outside
The trabeculae of the bone is located where?
in the medullary cavity
What are the 2 layers of the periosteum?
outer layer: fibrous
Inner layer: osteogenic
Once again, what are osteoprogenitor cells derived from?
derived from mesenchymal cells
What do osteoblasts come from? Where are they located? What can they turn into?
develop from osteoprogenitor cells line the inner periosteum endosteum Haversian canal **can become osteocytes after they gradually become surrounded by matrix
What is the function of osteocytes?
exchange of nutrients & waste w/ blood via canaliculi
What are osteoclasts derived from? What is their function?
come from bone marrow precursor
secrete enzymes, concentrate H+ & dissolve bone & calcium crystals. Release minerals into blood.
WHat is the order of cartilage to bone?
resting/reserve proliferation hypertrophy calcification ossification
What are the proteins of the bone?
Type I Collagen–90% of organic component
Non collagen products of osteoblasts
What are the 2 types of collagen deposition?
- woven bone: random weave, weaker structure
2. lamellar bone: slow deposition, strong
When do you see woven bone?
fetal skeleton
adult pathologic states like fractures, tumors, infections
**anything that requires rapid growth
When do you see lamellar bone?
in adults, replaces woven bone @ growth plates
What are some of the uncommon congenital malformations that can happen to bone?
Absence of a phalanx, rib, or clavicle
Extra bones (supernumary ribs, digits)
Fusion of adjacent joints (syndactylism)
Formation of long, spider-like digits (arachnodactylism) as is seen in Marfan’s syndrome
What is the most common disease of the growth plate? …a hereditary condition of abnormal growth
achondroplasia aka osteochondrodysplasia
messed up maturation of cartilage–>disorganized chondrocytes
Which mutation causes achondroplasia? What is the result?
- *caused by Fibroblast Growth Factor Receptor 3 mutation
* *results in dwarfism
Which hereditary pattern of achondroplasia is most common? What are the characteristics of this?
Heterozygous more common
aut dom
short extremities, bowed legs, lordosis, normal trunk, big head
normal life span, reproduction etc
What is it that causes the enlarged heads in heterozygous achondroplasia?
normal cranium & vertebrae
but frontal bossing & saddle nose
What happens in the less common homozygous achondroplasia?
compromised resp capacity
dead in infancy
GH unhelpful
What are mucopolysacchardisoses?
lysosomal storage disease
involving acid hydrolyses
**bad hyaline cartilage
**therefore, messed up growth plates & articular surfaces
See: chest wall deformities, short stature, malformed bones
What is osteogenesis imperfecta?
brittle bone disease
abnormal Type I Collagen formation–too little bone, multiple fractures
a condition of abnormal matrix
What is the clinical presentation of OI?
lax joints blue sclera (so thin you can see the veins!) deafness (fracture inner ear bones) thin skin small & discolored teeth
What exactly happens to the bone in OI?
cortical thinning
attenuation of bony trabeculae
woven bone instead of trabecular bone
What is OI often misdiagnosed as?
child abuse
What are the 4 major types of osteogenesis imperfecta?
- (aut dom) postnatal fractures w/ blue sclera & deafness
- (aut rec) perinatal demise
- (aut rec) progressive deformation & growth retardation, hard to survive
- (aut dom) postnatal fractures without blue sclera
Survivors of OI usu have an aut dom form. Types I & 4. What are their features?
hearing deficits
blue yellow teeth
all have fractures
Give 3 categories of metabolic disorders affecting bone.
Nutritional
Endocrine
Osteoporosis
Vit C deficiency can mess with bone as a nutritional metabolic disorder…leading to…
Scurvy
Vit D deficiency can mess with bone as a nutritional metabolic disorder…leading to…
Rickets & Osteomalacia
Soft bones w/ more osteoid & less mineralization
What is an example of an endocrine metabolic problem with bone?
hyperparathyroidism
What is osteoporosis? What are the different subtypes?
decreased bone mass & density=increased fragility
normal ratio of minerals to protein matrix
Can be local (w/ disuse) or diffuse
Can be primary or secondary
Which type of people suffer from primary osteoporosis?
postmenopausal women
senile people (men)
idiopathic in younger peeps
Which ethnicity is least likely to have osteoporosis?
African Americans
higher bone density
What are some osteoporosis risk factors?
- *Excessive alcohol, caffeine, carbonated beverages
- *Cigarette smoking
- *Anticonvulsants (phenytoin), Benzodiazepines (valium & xanax) - long term
- *Hypogonadism (decr. testosterone)
- *Hypercortisol states, therapeutic or adrenal pathology
- *Hyperparathyroidism
- *Inadequate Ca++ and Vitamin D in diet
When would an X-ray show osteoporosis?
only after 30-40% of the bone mass is depleted.
USE A DEXA SCAN
T/F Serum Ca++, Phosphorus, Alkaline pHosphatase are helpful in diagnosis of osteoporosis.
False.
Where do you often see fractures when you have osteoporosis?
painful vertebral fractures in thoracic & lumbar regions
loss of height
deformities: kyphoscoliosis, lordosis
fractures of wrist & weight bearing bones, femoral neck, pelvis, spine
How do people die from osteoporosis? How many people per year do die from it?
die from PE or pneumonia after immobility from fall
40K-50K per year die.
When do you reach your peak bone mass?
3rd decade of life
b/c with time osteoblasts & osteoprogenitor cells have decreased biosynthetic ability over time
after 30 yo, 0.7% decrease in mass/year
Where does the bone loss begin after the third decade of life?
begins in spin & femoral head
increased trabecular bone
What happens if you have calcium intake in adolescence?
esp common in adolescent girls
get lower peak bone mass
predisposed to osteoporosis
What are hormonal factors in osteoporosis?
deficiency in estrogen
deficiency in testosterone
**increased bone resorption
What is the mechanism of estrogen in healthy bones?
decreased estrogen
increased IL-1 from blood monocytes
IL-1 is a potent activator of osteoclasts
osteoblasts activated, but not as much
bones w/ increased surface area (like trabecular bone of vertebral bodies)–>micro fractures!
What is a notable bone disease of osteoclast dysfunction?
Pagets Disease aka osteitis deformans
What are the 3 phases of Paget’s?
Phase 1: osteolytic (osteoclasts active (10-12 nuclei) & predominate), hypervascular, bone loss
Phase 2: Mixed osteoclast/osteoblast, but osteoblasts predominant.
Osteosclerotic Phase: Burn out!
What happens to the bone marrow in Paget’s disease–phase 2?
replaced by CT that has osteoprogenitor cells & blood vessels
What does the bone end up looking like after the phases of Paget’s?
mosaic, jig saw puzzle
woven bone present
weak & prone to fractures
What age group & race do you usu seen Paget’s in?
Age group: 5th decade
Race: Northern Europe & US, excluding Scandinavians
What is thought to cause Paget’s disease?
a slow virus, paramyxovirus-like deal found in osteoclasts
virus induces production of IL-6, activates osteoclasts
What percentage of Paget’s cases are monostotic (1 lesion)? Where are these lesions usu located?
10%
tibia, ileum, femur, skull, vertebrae, humerus (more proximal things)
What percentage of Paget’s cases are polyostotic (multiple lesions)? Where are these lesions located?
90%
pelvis, spine, skull (more axial skeleton)
What are the symptoms of Paget’s disease?
often asymptomatic headache, hearing loss, visual problems pain localized to bone b/c of micro fractures or bone overgrowth into nerve leonine facies bowing bones w/ weight
What is leonine facies?
overgrowth of craniofacial bones
- *also seen in leprosy
- *difficult to stand upright b/c of weight of bone
What can happen to blood flow in severe polyostotic disease?
increased blood flow w/ a fcnl AV shunt
high output cardiac failure
Which bone tumors are seen in paget’s disease?
giant cell tumor (benign)
sarcomas (seen w/ severe polyostotic disease)
T/F Extramedullary hematopoiesis is seen in Paget’s b/c of depletion of normal bone marrow after the 3 phases.
True!
What are the lab findings in Paget’s? Note: not that helpful in diagnosis.
Non-specific, but include:
elevated serum alkaline phosphatase
elevated urinary hydroxyproline
Normal serum calcium and phosphate
WHat is the treatment for Paget’s?
anti-resorptive agents that inactivate osteoclasts
Bisphosphonates (Fosamax)
calcitonin
What is osteopetrosis?
Stone Bone or Marble Bone
abnormally brittle bone
can cause osteosclerosis
**one type exhibits carbonic anhydrase II deficiency (necessary to acidify an environment–osteoclasts can’t do their thing)
In Osteitis fibrosa cystica...what's the deal with the following: calcium phosphate alkaline phosphatase PTH other characteristics?
calcium: up
phosphate: down
alkaline phosphatase: up
PTH: up
other characteristics? brown tumors
In osteomalacia & rickets...what's the deal with the following: calcium phosphate alkaline phosphatase PTH other characteristics?
calcium: down
phosphate: down
alkaline phosphatase: up
PTH: up
other characteristics? soft bones
In osteopetrosis...what's the deal with the following: calcium phosphate alkaline phosphatase PTH other characteristics?
calcium: normal
phosphate: normal
alkaline phosphatase: up
PTH: normal
other characteristics?
thick dense bones aka marble bone
In osteoporosis...what's the deal with the following... calcium phosphate alkaline phosphatase PTH other characteristics?
calcium: normal
phosphate: normal
alkaline phosphatase: normal
PTH: normal
other characteristics?
decreased bone mass
In Paget's disease...what's the deal with the following? calcium phosphate alkaline phosphatase PTH other characteristics?
calcium: normal
phosphate: normal
alkaline phosphatase: variable by stage
PTH: normal
other characteristics?
abnormal bone architecture
Give an example of a bone problem that has defective mineralization v. defective metabolism. What’s the difference?
Vit D deficiency–defective mineralization. Increase in osteoid
Osteoporosis–defective metabolism. Mass decreased, but bone is normal.
What is the precursor to Vit D3 in the skin? In the plant food?
Skin: 7-dehydroxycholesterol
Plant Food: ergosterol
What does Vit D bind to for transport in the body?
alpha 1 globulin (d binding protein)
What is VIt D converted to in the liver? In the kidney?
Liver: converted to 25-OH Vit D
Kidney: 1,25 OH2 active form
What are the 3 mechanisms that regulate Vit D?
- elevated active Vit D3 inhibits alpha hydroxylase in kidney
- hypocalcemia–>PTH up–>alpha hydroxylase activated
- hypophosphatemia–>alpha hydroxylase activated
What are the functions of VIt D?
- stimulates intestinal absorption of Ca++ & phosphate
- w/ PTH mobilizes Ca++ from bone
- w/ PTH causes reabsorption of Ca++ from renal tubules
What is the function of VIt D during times of hypocalcemia?
works with PTH
maintains plasma level of ca
What is the mineralization function of VIt D?
required for normal mineralization of epiphyseal cartilage & osteoid matrix
What is the effect of Vitamin D Deficiency?
hypocalcemia in blood
**either too much resorption of bone then results or lack of proper mineralization
What are some factors that can cause Vit D Deficiency?
not enough sunlight decreased intestinal absorption enhanced degradation b/c of drugs--affects cyt p450 liver disease renal disease
What is the basic lesion of VIt D Deficiency?
excess of unmineralized matrix
What happens in rickets?
overgrowth of epiphyseal cartilage
deposition of osteoid matrix
Disruption of orderly replacement of cartilage by osteoid matrix, with enlargement and lateral expansion of osteochrondral junction
Abnormal growth of capillaries and fibroblasts in disorganized zone because of microfractures
Deformation of skeleton due to loss of structural rigidity of developing bones
What are the clinical manifestations of Rickets?
frontal bossing rachitic rosary pidgin breast Harrison's groove deformities of pelvis, long bones, lumbar lordosis & bowing of legs
What is rachitic rosary?
deformation of chest from overgrowth of cartilage or osteoid at costochondral junction
**Rickets
What is pidgeon breast?
anterior protrusion of the sternum
pull of resp muscles on the weak metaphyseal areas of ribs
**Rickets
What is Harrison’s groove?
girdling of thoracic cavity at lower margin of rib cage due to pull of diaphragm
What is osteomalacia?
Derangement of remodeling process that occurs throughout life
Newly formed osteoid matrix is inadequately mineralized, with resultant Excess of persistent osteoid
Contours of bone not affected, but Bone is weak and prone to microfractures, most likely affecting vertebral bodies and femoral necks
PTH regulates homeostasis of what? Increased Parathyroid hormone levels cause what?
Calcium!
stimulate osteoblast receptors
release mediators
increase osteoclast activity
Which is more severe..primary or secondary hyperparathyroidism?
primary is more severe
The changes involved in hyperparathyroidism are collectively known as what?
osteitis fibrosa cystica
Which type of bone is more affected by hyperPTH…
cancellous or cortical
Cortical more affected!
What happens to teeth with HyperPTH?
subperiosteal resorption produced thin cortex
loss of lamina dura around teeth
teeth are loosened!!
What causes the brown tumors of hyperparathyroidism?
microfractures & secondary hemorrhages cause influx of multinucleated macrophages & fibrous tissue. Form tumor.
What is renal osteodystrophy?
skeletal changes due to chronic renal disease
See:
Increased osteoclastic bone resorption which mimics osteitis fibrosa cystica
Delayed matrix mineralization (osteomalacia)
Osteosclerosis
Growth retardation
Osteoporosis
What is the mechanism of renal osteodystrophy?
renal failure–phosphate retention
hyperphosphatemia causes hypocalcemia–causes secondary hyperparathyroidism
kidneys damaged–less active Vit D
inhibited renal hydroxylase b/c of high phosphate levels
reduced intestinal absorption of Ca++ b/c of that low VIt D
What is the result of increased PTH levels in renal osteodystrophy?
Increased osteoclast activity
parathyroid glands more sensitive to depressed calcium
PTH retained in body
Low levels of VIt D3 & Ca++ in renal osteodystrophy contribute to the progression to what?
osteomalacia
Strangely, iron accumulation happens in renal osteodrystrophy. What is another deposition in bone due to the drugs used to bind phosphate?
aluminum deposition in bone
What is a simple fracture? A compound fracture?
simple: if overlying tissue is intact
compound: if skin is broken
What is a comminuted fracture?
if bone is splintered
What is a displaced fracture?
if ends of bone at fracture site are not aligned
What is a stress fracture?
if fracture develops slowly b/c of increasing repetitive loads that cause a break
Describe briefly the process of a bone fracture healing.
fracture blood clot bone near the break is dead fibroblasts move in & build on the fibrin matrix osteoclasts & vessels move in cartilage forms first then woven bone (non weight bearing) months later: lamellar bone
What is avascular necrosis? What are other names for it?
**necrotic bone due to ischemia--usu in hip aka bone infarction osteonecrosis aseptic necrosis ischemic bone necrosis
What are possible causes of avascular necrosis?
prior steroid admin
idiopathic!
Other possibilities: CT disease, sickle cell (plugs small vessels of bone during crisis), radiation, alcohol abuse, tumors, trauma
What are the 2 types of avascular necrosis?
subchondral infarct: triangular articular cartilage viable b/c of synovial fluid contact
medullary infarct: cortex uninvolved due to collateral blood flow
What is the clinical course of subchondral infarcts? Medullary infarcts?
Subchondral: chronic pain, if cartilage collapses-severe osteoarthritis
Medullary: silent & stable
**associated with Gaucher’s disease (sphingolipid accumulation)
dysbarism
hemoglobinopathies
What is the cause of pyogenic osteomyelitis?
bacteria (extension from acute infection of an adjacent joint)
traumatic implant after fracture
usu staph aureus!
In neonates with pyogenic osteomyelitis…what is usu the causative organism? In sickle cell patients? With trauma?
Neonates: E coli or group B strep
Sickle Cell: Salmonella
Trauma: Mixed bacterial infections
Where do pyogenic osteomyelitis abscesses usu form in children? In adults?
Children: the metaphysis
Adults: anywhere
**can sometimes turn into a squamous cell carcinoma if it leaks into a sinus
What is chronic osteomyelitis?
follows an acute infection
no more neutrophils, now lymphocytes & plasma cells
residual necrotic bone can be resorbed by osteoclasts or surrounded by a rim of new reactive bone
What is sequestrum?
residual necrotic bone seen in chronic osteomyelitis
What is involucrum?
big sections of residual necrotic bone surrounded by a rim of reactive new bone
What is a Brodie’s abscess?
well defined rim of sclerotic bone around a residual abscess
What are the symptoms of chronic osteomyelitis? What are the imaging studies? What is the treatment?
symptoms: fever, malaise, leukocytosis
Routine radiographic
Radionuclide scan (gallium)
Treatment: vigorous antibiotic therapy
What can be some bad results of chronic osteomyelitis?
pathologic fractures
bacteremia
endocarditis
**sometimes amyloidosis, squamous cell carcinoma in sinus tracts
What is tuberculosis osteomyelitis?
spread via blood usu
seen in AIDs patients
bacillus starts the infection in synovium where there is oxygen & then it spreads to the bone
spinal lesions spread to adjacent soft tissue (pott’s disease)
What is the most common malignant tumor of the bone?
osteogenic sarcoma
Usu if you see a bone tumor in the first 3 decades of life…is it benign or malignant? In elderly?
Younger people: benign
Elderly: malignant
How are bone-forming tumors usu deposited? What are osteomas?
deposited as woven trabeculae
variably mineralized
Osteomas: oval projections from subperiosteal or endosteal surfaces of the bone cortex
Are osteomas malignant?
No! They are benign.
Look like normal bone under histo.
Can impinge on brain, eye function
Which syndrome is associated with multiple osteomas on the skull?
Gardner’s Syndrome
WHile osteoid osteomas & osteoblastomas are identical on histo…they have a size difference. What is it? What are other shared features?
Osteoid Osteomas: 2 cm in size **occur in 20s & 30s begin small, round, radiolucent "nidus" that becomes sclerotic or mineralized w/ a rim of bone they are well circumscribed will recur if not excised
What are distinguishing features of osteoid osteoma?
peripheral skeleton–femur or tibia
painful at night
too much prostaglandin E2
relieved by aspirin
What are the distinguishing features of osteoblastomas?
spine involved
possibly painful–dull ache
aspirin ineffective
How does osteogenic sarcoma form?
malignant mesenchymal cells form in the bone matrix
p53 tumor suppressor gene mutates
usu occurs in the metaphysics of long bones, often in the knee
usu <20 yo
If osteogenic sarcoma is secondary…what is the original cause?
Paget’s disease
radiation
WHat does osteosarcoma look like microscopically?
islands of primitive bony trabeculae
rim of malignant osteoblasts
What is the course of osteosarcoma?
aggressive lesions
metastasize via blood
lung mets 20% at the time of initial diagnosis
What is osteochondroma?
most common benign tumor in bone
mature bone with a cartilaginous cap (cauliflower look)
arise from metaphysics near growth plate of long bones, anchored to the cortex
asymptomatic
What is endochondroma aka chondroma?
benign lesion of mature hyaline cartilage
usu seen in short tubular bones of hands & feet
asymptomatic, but could be painful
in 1/3 of patients–could be a chondrosarcoma
What is Ollier’s disease?
multiple endochondromas
on one side of the body
What is Maffucci’s syndrome?
multiple endochondromas
associated with hemangiomas of soft tissue
What is chondrosarcoma?
matrix forming bone tumor seen in middle-aged & older people associated with endochondroma starts in medullary cavity central skeleton affected mets to lungs
What is the giant cell tumor of the bone?
occurs in epihpyses of long bones
usu benign
soap bubble appearance on radiology
neoplastic mononuclear cells–abundance reactive osteoclast-like multinucleated cells
What gender & age group does giant cell tumor of bone usu occur in?
more often in females
20-40yo
What is Ewing’s Sarcoma?
2nd most common childhood malignancy of bone affects femur, tibia, pelvis usu pain & inflammation expanding intramedullary mass abundant necrosis
Due to the abundant necrosis what is ewing’s sarcoma sometimes misdiagnosed as?
osteomyelitis
Somehow related to Ewing’s Sarcoma…a translocation t(11,22) can cause what?
primitive neuroectodermal tumors
What does Ewing’s sarcoma look like on histo?
small blue cell tumor
sheets of small cells with uniform nuclei
contain glycogen
What is multiple myeloma?
pockets of plasma cells
abundant cytoplasm, large eccentric nuclei with clock face chromatin
produce Ig
What is fibrous dysplasia?
benign tumor like condition with possible fractures
fibrous tissue replaces normal trabecular bone–get disorderly islands of deformed bone
mono-ostotic (more common) & poly-ostotic form
What’s the deal with the mono-ostotic form of fibrous dysplasia?
begins in adolescence
happens in ribs, calvarium, femur, tibia, jaw
What’s the deal with the poly-ostotic form of fibrous dysplasia?
adulthood issues
craniofacial involvement
associated with endocrine abnormalities
unilateral bone lesions & cafe au lait spots
What is osteoarthritis?
most common disorder of joints
not inflammation
degeneration of articular cartilage–wear & tear
usu primary
can be secondary to a deformed joint from a metabolic disease
What are the changes in composition & mechanical properties of cartilage seen in osteoarthritis?
increased water & decreased proteoglycans
weakening of collagen network (type II)
chondrocytes secrete IL-1–this activates proteolytic enzymes & collagenases
WHat is the eburnation that happens with osteoarthritis?
subchondral bone becomes thickened
gives appearance of ivory
HOw can cysts form in the bone with osteoarthritis?
form in the bone as cracks in cartilage allows synovial fluid to leak in.
What are Herberden’s nodes in osteoarthritis?
these are osteophytes on distal interphalangeal joints
What is rheumatoid arthritis?
systemic chronic inflammatory disease
affects many organ systems, including joints
more often in females, 40s & 50s
What is the clinical presentation of rheumatoid arthritis?
morning stiffness heat & movement alleviate joint swelling, redness, warmth neutrophils present radiology shows erosions **usu small joints & symmetric joint involvement not DIP joints
What types of cells are seen in the synovium & synovial fluid of a rheumatoid arthritis patient?
infiltration of lymphocytes, macrophages, plasma cells in synovium
neutrophils may be in the synovial fluid
synovial lining cells proliferation & become hypertrophic
see villous projections
sometimes see lymphoid follicles
Where do subcutaneous nodules form in a rheumatoid arthritis patient? What do they look like microscopically?
at areas of pressure, maybe elbow microscopically: fibrinoid necrosis palisading macrophages rim of granulation tissue
Infectious Arthritis (suppurative) is usu caused by which bacteria? What are some predisposing factors for this ?
most commonly: GC, staph, strep, H influenza, gram neg rods salmonella-sickle cell patients Factors: immunodeficiency joint trauma IV drug use
Infectious Lyme Disease is caused by which organism? Pathway of infection? AFfect on joints?
Borrelia Burgdorferi Rodents--Humans via deer ticks joints: ones that are large can look like rheumatoid at first extensive erosion of large joint cartilage
WHat is gout?
uric acid (from purine metabolism) accumulation as monosodium irate crystals in joints
recurrent episodes of acute arthritis–esp in 1s metatarsal
tophi
What do the monosodium urate crystals look like microscopically?
needle-shaped
birefringent: look yellow in one direction & blue in another
What are tophi?
large accumulations of crystalline material in soft tissue
can create a chronic granulomatous reaction
Most gout is primary & is caused by what?
overproduction of uric acid
unknown enzyme defects
10% of gout cases are secondary. to what for example?
lymphoma or leukemia treatment
as tumors are lysed–proteins released for degradation
chronic renal insufficiency-can’t get rid of the uric acid
lesch-nyhan syndrome-lack of HGPRT enzyme
T/F Urate crystals in synovium of a gout patient are chemotactic & active complement, attract neutrophils & macrophages to joint & synovium & create arthritis.
What do you know–true!
What is pseudo gout?
deposition of calcium pyrophosphate crystals
found in knee after trauma or surgery
can be associated with systemic disease–like hemochromatosis
Which joints are often associated with pseudo gout? HOw long do the attacks last?
1 day-4 weeks
involves knees, ankles, wrist, elbow, hips, shoulders
How do the crystals appear microscopically in pseudo gout?
coffin-shaped
weakly bi-refringenet
Where do the calcium pyrophosphate crystals of pseudo gout come from?
nucleosides in chrondocytes
What is a motor unit?
motor neuron w/ a peripheral axon that extends to another motor neuron & connects via a neuromuscular junction
What is neurogenic atrophy of skeletal muscle?
happens when muscle is deprived of normal innervation
progressive atrophy of Type 1 & 2 fibers
What are the clinical features of neurogenic atrophy?
muscle weakness
in infants: floppy baby syndrome
What is the morphology of neurogenic atrophy?
atrophy in small group clumps b/c one nerve supplies one motor unit
T/F Type I fibers are fast twitch.
False. They are slow twitch.
It is difficult to distinguish neurogenic atrophy from other types of atrophy related to type II myofibers. What are the causes of fast twitch atrophy?
disuse
glucocorticoid use that is longterm
hypercortisol state
What is myasthenia gravis?
acquired autoimmune disorder of neuromuscular junctions
more common in females
antibodies form to the acetylcholine receptor
some sort of relationship w/ a messed up thymus
What are some clinical features of myasthenia gravis?
ptosis or diplopia
facial & neck muscles or resp muscles can be messed up
progressed throughout the day
What is the treatment for myasthenia gravis?
anticholinesterase agent (edrophonium chloride)
cholinesterase inhibitors
thymectomy
What’s the deal with Duchenne Muscular Dystrophy?
x-linked, affects more males
muscle weakness, proximal
calf muscles weak & large
absence of structural proteins (dystrophin)
What does DMD look like microscopically?
CT increased
marked variation in muscle fiber size
hypertrophy & atrophy of adjacent fibers
WHat’s the deal with Becker Muscular Dystrophy?
X linked
mutation in dystrophin
less severe than DMD
What is rhabdomyoma?
cardiac muscle neoplasm associated with tuberous sclerosis
What is rhabdomyosarcoma?
most common soft tissue sarcoma in peds
What are some other variants of rhabdomyoma?
embryonal–head neck GU, retroperitoneal
Alveolar
Pleomorphic Type
When a rhabdomyoma is found in the GU tract what is it called?
sarcoma botryoides
it looks gelatinous & grape like structures are present
may be primitive small round blue cells with scattered strap cells (skeletal muscle)
How are soft tissue tumors classified?
fat, muscle, fibrous tissue
What are the associative “causes” of soft tissue tumors?
Radiation therapy Chemical and thermal burns Trauma Exposure to some organic chemicals AIDS/Kaposi’s sarcoma/virus
What is a lipoma?
most common soft tissue tumor
benign slow growing masses, usu painless
comprised of mature fat cells, yellow in color
What is a painful form of a lipoma? How is it cured?
angiolipoma: local pain on velar surface of the forearm
* *cured by simple excision
What is a liposarcoma?
arise in deep tissues of proximal extremities or retroperitoneum
can also be in lower extremities or abdomen
appear in 50s or 60s
WHat is nodular fasciitis?
a fibrous tissue tumor
most commonly found in upper extremities & trunk
grow rapidly!
hx of trauma sometimes in patients
Is a nodular fasciitis a neoplasm? WHat is its sometimes confused with?
No, not a true neoplasm. Caused by an over-reaction of fibroblasts.
**can be confused with sarcoma b/c of cellularity
What is fibromatosis?
group of fibroblastic proliferations
infiltrative
recur after excision
deep form more aggressive than superficial
T/F Fibromatosis is an example of a true neoplasm.
False.
What are the 2 superficial types of fibromatosis?
Duptyren’s contracture (palmar fibromatosis)
Peyronie’s DIsease (penile fibromatosis)
What is the name of the tumor included in the deep fibromatosis?
desmoid tumor
WHat is a fibrosarcoma?
comprised of fibroblasts
originates in fibrous tissues of bones & invades long or flat bones like femur, tibia, mandible
favors deep tissues of thigh, knee, trunk
metastasizes to the lungs via blood
Central fibrosarcoma arises from where?
intramedullary canal
Peripheral fibrosarcoma arises from where?
arising from periosteal tissues
What is the infantile-type of fibrosarcoma?
usu congenital
presents in first 2 years of life
What is the common age & gender for fibrosarcoma?
male
30-40
WHat are fibrohistiocytic tumors?
benign–aggressive malignant tumors
most important type: malignant fibrous histiocytoma
aka pleomorphic sarcoma
favored sites: lower limbs & retroperitoneal areas
What is the prompt of a fibrohistiocytic tumor? Which age do you usu see this in?
post-irradiation
50s-70s
What is a synovial sarcoma?
arises from mesenchymal cells around joint cavities–not from synovial cells!
develop in vicinity of large joints of lower extremities, esp the knee
