Bone Pathology Flashcards
What is the term for demineralization of bone seen on x-ray?
osteopenia
What are the 4 main causes of osteopenia? Which is most common?
osteoporosis is most common
osteomalacia
malignancy
rare hereditary disorders
Are neoplasms involving bone usually primary neoplasms or metastases?
metastases
What is a pathological fracture?
a fracture thorugh diseased bones - usually refers to a fracture through tumorous or tumor-like bone
How do the growth plates close in puberty?
sex hormones signal blood vessel incursion through the cartilage, which causes it to mineralize and the plate closes.
How much of the total body calcium is in bone?
99 percet
Low serum calcium levels will trigger secretion of what hormone to induce calcium release from the skeleton?
parathyroid hormone - triggers osteoblasts to activate the osteoclasts
Why is VItamine D such an important molecule for the skeleton?
It helps get calcium from the gut into the blood so that bone mineralization can occur
Whta needs to happen to vitamin D before it can be useful?
It needs to by hydrosylated twice - first in th eliver and then in the kidney in the presence of PTH.
What molecule will inhibit the hydroxylation of vitamin D?
phosphate
and vit D(OH2) itself
What is unique about the blood clot that forms in fractures?
It will become fibrous like other blood clots, but then it will mineralize!
What reaction will the periosteum have in response to bone trauma?
It will lay down new bone
What are some complications of fractures thorugh healthy bone?
mal-alignment
non-union / pseudoarthrosis
osteomyalitis (especially in compound fractures)
growth disturbance (in kids)
arthritis (if fracture is intraarticular)
fat embolism syndrome
PE - from immobilization
Osteoporosis of immovilized bone
what is osteoporosis?
a type of osteopenia due to bone atrophy caused by an imbalance of the bone remodeling process - more osteoclast activity than osteoblast
its definitely age related, and much more in women
What are the clinical manifestations of osteoporosis?
pretty much asymptomatic until they get a fracture
vertebral fractures are the most common:
compression fractures (pancake fractures) are acutely painful, while wedge fractures (more common) are usually painless and just cause them to slowly stoop and shorten
What are some causes of osteoporosis?
low estrogen postmenopause
excess corticosteroids
hyperparathyroidism
hyperthyroidism
poor nutrtiion or malabsorption
immobilization
hypogonadism
WHy should you keep osteoporosis as a diagnosis of exclusion?
Becuase there are causes of secondary osteoporosis which are much more treatable and even reversible
osteopenia does NOT = osteoporosis
In osteopenia, is it the compact or cancellous bone that really demineralizes?
the cancellous bone.
Why do you get kyphosis in severe osteopenia?
You get wedge fractures of the anterior vertebral bodies under the weight of the head.
Besides the spine, what are some bones that are commonly affected by osteoporosis?
any bone that’s near key stress joints like the proximal femur, proximal humerus and distal radius
it will NOT take much force to break these
What is the best prevention for osteoporosis?
maximize peak bone mass in young adulthood and encourage weight bearing exercise and Ca and Vit D supplementation
What is the strongest predictor of ostoporosis risk?
maternal hip fracture
What is the actual way to diagnose osteoporosis - not an x-ray after a fracture?
bone densitometry
diagnose if they are under 2.5 deviations of the average for a yount adult
Most anti-osteroporosis meds inhibit what?
osteoclast bone resorption
Hypercalcemia is almost always due to what?
a primary hyperplasia or neoplastic enlargment of the parathyroid glands
Which type of bone is more resorbed in hyperparathyroidism - trabecular or cortical?
cortical
What are some complications of primary hyperparathyroidism?
fractures due to demineralization
metabolic impariment of the kidneys and renal stone disease (because of the excess calcium)
muscle weakness
neuropsychiatric syndromes
In hyperparathyroidism you will see ___ serum calcium and ____ serum phosphorus.
elevated Ca and decreased P
What is osteomalacia?
It’s decreased bone mineralization with excess osteoid due to an interference with calcium, phosphate, or vitamin D metabolism - sometimes hard to tell the difference
it will be osteopenic on radiology
How is the presentation for osteomalacia different from that of osteoporosis? 1 important distinction…
osteomalacia can present with diffuse skeletal pain without fracture while osteoporosis will be asymptomatic until the fracture
What can cause osteomalacia?
- rickets (environmental)
- Intestinal malabsorption - commonest cause of Vit D deficiency in the US
- Liver or renal disease - impaired hydrosylation of Vit D
- Rare congenital errors of metabolism
What will labs show in osteomalacia?
increased serum alkaline phosphatase becuase the osteoblasts are trying to repair…
low serum Ca or P
decreased urinary Ca excretion
Increased PTH - attempt at a compensatory mechanism
decreased in hydrosylated vitamin D
What will a vitamin D deficiency in children (rickets) cause?
widened/shortened growth plates
bowed legs due to softened bone
fractures
What is “renal rickets”?
Renal osteodystrophy
it’s a progressive destruction of the second hydroxylation of Vitamin D in the kidneys
most commonly a combination of secondary hyperparathyroidism and abnormal mineralization
Under histology, what is the hallmark of osteomalacia?
osteoid seams - the osteoid is layed down by the osteoblasts but doesn’t mineralize
WHat is the primary mode of acquisition for an osteomyelitis in children? In adults? In diabetics?
kids: hematogenous spread to bone from an occult source
adults: direct infection through compound fractures or orthopedic procedures
diabetis: secondary infection through an adjacent contiguous infection like joint or soft tissue infections - usually feet
Which bones are most often affected by osteomyelitis?
long bones - usually starts in the metaphyseal region
How do you definitivly diagnose an osteomyelitis?
take a direct bone culture
blood cultures will work too, but children may culture negative
they’ll also have fever, high WBCs and bone pain - the bone pain without acute injury is the big tip off
What is the most common microorganism for osteomyelitis?
staph auerus 95%!
Some streptococcus, gram negative bacilli and salmonella in sick cell patients
Which radiological technique is better for catching an osteomyelitis?
MRI are better at early detection
x-ray won’t see it until about 10 days after it starts
WHat are some potential chronic complications of suppurative osteomyelitis?
suppurative arthrtis of the adjacent joints
sinus tracks to skin - drianage
growth disturbance in kids
deformity
amyloidosis - in any chronic inflamatory condition
What is the treatment for osteomyelitis?
aggressive!
IV antibiotics
can use surfical drainage/deridement
amputation in chronic cases
What bones does TB usually spread to? WHat is this called?
spine and long bones
if in the spine = Pott’s disease
What are the two major fungi that can cause osteomyelitis?
blastomycosis is the most common in immunocompetent patients
coccidioidomycosis
always secondary to hematogenous spread form lungs
WHere in the long bones does osteomyelitis often start?
the metaphysis
Where do spinal osteomyelitises start?
hematogenous spread directly into the disc, from there is goes into the disc above and below
What are the most common causes of avascular bone necrosis/infarction?
fractures is the big one
corticosteroid Rx
alcoholism
Which bone is most commonly affected by abascular necrosis?
femoral head
What is the difference between a subchondral infarct and a medullary infart?
subchondral infarcts are in the epiphyses and affect the joint - causing pain wtih activity
medullary infarcts are infarcts of the shafts of bone and can be clinically silent unless they get very large (which they can) and cause fractures
What are the complications of avascular bone necrosis?
secondary degenerative joint disease
bone growth deformities in kids
pathologic fracture
What is Paget’s Disease of bone (osteitis deformans)?
it’s a deforming bone disease in middle aged ango-saxons
due to a latent viral infection of osteoclasts in a genetically susceptible person
usually makes large bones (skull, pelvis, tibia, etc) larger
What are the 3 phases of paget’s disease of bone?
- lytic: increased osteoclasts with bone resorption and increased vasculatiry
- Mixed: increased osteoclast activity and increased osteoblast activity (as a componsation)
- Sclerotic: increased osteoblastic phase - most characteristic radiologically
True or false:
Paget’s disease of bone causes widening slcerosis of the bone, and with that, a reduced risk of fractures.
False
It does widen bones and make them bigger, but ironically it also makes the bones weaker and more likely to fracture
Paget’s disease of bone is usually asymptomatic, but what are some symptoms that can occur?
principally pain due to fractures, compression of cranial nerves or spinal nerves
or pain from secondary degenerative joint disease due to subchondral bone deformity
sometimes the skin overlying an affected bone is warm during lytic/vascular phase
What lap finding will be significant in Paget’s disease of bone?
increased serum alkaline phosphatase (without liver disease)
What are 4 major congenital bone disorders? Which are we most likely to see in our offices?
neural tube defects
achondroplasia
osteogenesis imperfecta - most common we’ll see
osteopetrosis
What is osteogenesis imperfecta a disorder of?
type 1 collagen synthesis - either abnormal or not enough
as a result you have insufficient collagen for normal osteoid production and you get brittle bones and slow growth (causes osteopenia)
What is osteopetrosis a disorder of?
osteoclasts - they dont resorb bone normally so the bones get huge.
the cure for this is a bone marrow transplant
very rare
Using x-ray, bone tumors can be classified as either ___ or ______ or mixed.
osteolytic (demineralizing)
osteoblastic (increased bone density)
What is the classic example of a purely osteolytic maligancy? How about a ostoblastic malignancy?
osteolytic = myeloma
osteoblastic = metastatic prostate cancer
Metastatic tumors are the most common malignancies to bone. What are the most common source cancers?
lung breast and prostate
but pretty much every malignant neopplasm is capable to metastasizing to bone
Which bones are the more common sites of mets?
larger bones but can be anywhere
What are the four hemic malignancies often affecting bone?
classic myeloma
plasmacytoma
lymphoma
leukemia
What does plasmacytoma of bone (localized tumor of plasma cells) frequently evolve into?
classic myeloma
Most non-Hodgkins lymphomas involve bone as a secondary or primary lesion?
secondary
How do you diagnose myeloma on pathology?
blood smear shows huge ugly plasma cells
What are some clues on x-ray that a bone cancer is malignant?
areas of demineraization and hypermineralization - unable to draw a nice line around the areas
penetrates the bone cortex
infiltrates surrounding STs
Where do primary bone tumors most often arise?
metaphyses of long bones
What are the most common benign tumors of bone?
osteochondroma
giant cell tumor
chondroma
osteoid osteoma
fibroma (metaphyseal fibrous defect)
What are the most common malignant tumors of bone?
osteogenic sarcoma (osteosarcoma)
chondrosarcoma
lymphoma
Ewing’s sarcoma
Chordoma
Which is the most common primary malignant tumor of bone in children and young adults?
Middle aged and older adults?
young = osteosarcoma
old = chondrosarcoma
Most benign cartilage tumors (chondromas) involves ___ bones while malignant cartilage tumors (chondrosarcomas) tend to involve ___ bones.
benign = small bones
malignant = large bones
Malignant bone tumors tend to spread through blood or lymph?
blood
What is the commonest bone lesion?
metaphyseal fibrous defect - fibroma
benign developmental defect found in a third of children - often regress spontaneously
What does an osteochondroma look like?
It’s a bony stalk of bone with a cartilage cap
basically, a piece of the epiphyseal frowth plate broke up and moved down to establish on the shaft. then ti started forming a new long bone.
Where do chondromas of bone usually occur?
in the small bone - particularly hands
you’ll see calcification on x-ray
If you have a kiddo with bone pain occurring at night that’s relieved by aspirin, what is the likly diagnosis?
osteoid osteoma
Where do giant cell tumors occur in bone?
Usually lytic or blastic?
epiphysis
lytic - it’s basically just huge osteoclasts
Osteogenic sarcoma prefers metaphyseal regions of large long bones, especially the…
knee
Osteogenic sarcoma may be secondary to…..3
paget’s disease of bone
prior irradiation
old bone infarcts
Most sarcomas will metastasize to the….
lungs
CHondrosarcoma prefers large long bones and central skeleotn especially the….
pelvis
chondosarcoma has the world record for…
forming the largest tumors
What is the most aggressive/lethal of the primary bone tumors?
Ewing’s sarcoma
Ewing’s sarcoma affects what type of bone preferentially?
the DIAPHYSIS of long bones and flat bones of pelvis
Ewing sarcoma is composed fo small undifferentiated tumor cells known as…
primitive neuroectodermal neoplasm (PNET)
