Bone Pathology Flashcards
Dysostoses
Abnormalities in a bone or a single group of bones
-arise from defects in migration and condensation of mesenchyme
Disorders of bones are catagorized by what?
Specific Genetic defect
Osteopetrosis
Autosomal recessive genetic disorder in deficient CA2 metabolic enzyme.
Often fatal in uterine and if not develops cranial nerve defects and leukopenia
Affected infants have cranial nerve defects and increased infections due to leukopenia.
Treatment of osteopetrosis
Steam cell treatments generate new osteoclasts which can reverse the marble bone build up.
Mucopolysaccharidoses
Lysosomal storage disease disorder
Defect In degrading dermatan, heparan, keratan sulfates
mucopolysaccharides accumulate in chondrocytes and cause premature apoptosis and structural defects in cartilage.
- marked by short stature, chest wall abnormalities and malformed bones.
Dysplasia
Global disorganization of bone and/or cartilage
Acquired disorders of bone
Osteopenia and osteoporosis
Paget disease
Osteomalacia
Hyperparathyroid
Renal ostodystrophy
Osteopenia vs osteoporosis
Osteopenia: decease bone mass with between 1-2.5 SD below average mean
Osteoporosis: decrease bone mess with less than 2.5 SD below average mean
- increases fracture risk
Osteoporosis pathogenesis
Often caused by menopause and natural aging.
Menopause
- Decreased estrogen and increased RANK/RANKL
- Also increased IL-1/6 and TNF levels
Aging
-decreases osteoprogenitor replication and synthetic osteoblast activity
Senile osteoporosis
Core thinned by superiosteal and endosteal respiration.
Haversian systems are widened and can resemble cancellous bone.
Clinical outcomes of osteoporosis
Loss of height, increased kyphosis of kyphosis regions, decreases lumbar lordosis
- can develop PE and pneumonia
- marked by 40-50% bone loss (when it can actually be detected)
Common preventative measures for osteoporosis
- Exercise
- Ca+ and Vitamin D supplements
- Bisphosphonate suppliments
- hormonal therapy (only when caused by postmenopause)
Paget disease
Increased but disordered bone mass
Possess three phases
- osteolytic phase
- mixed osteoclastic-osteoblast is phase
- burned out quiescent osteosclerotic phase
Paget disease morphology
Mosaic pattern of lamellar bone (commonly seen in sclerotic phase)
Clinical signs of Paget disease
- Pain and enlarged skin as well as osteoarthritis often accompany
- most commonly found in femur or axial skeleton.
- can be accompanied by excess heat in skin, increased blood flow, and tumor-like conditions
- can lead to heart failure
- have elevated alkaline phosphate but normal calcium levels
Treatment of Paget disease
Calcitonin and biphosphates
Rickets and osteomalacia causes
Vitamin D deficiencies
- marked by impairment of mineralization of the matrix.
Rickets = children and affects growth plates directly
Osteomalacia = adults and affects bone modeling directly
Hyper parathyroidism
- Increases osteoclast activity
- reabsorption of calcium in the kidney
- increased urinary excretion of phosphates and synthesis of active vitamin D
Renal Osteodystrophy
Tubular dysfunction and generalized renal failure causes decreased secreted factors.
- increases bond resorption by high amounts and ultimately can causes osteopenia, osteoporosis and osteomalacia, and growth retardation.
Hyperparathyrodism secondary pathology
often causes osteoporosis, brown tumors and osteitis fibrosis cystica
Simple fracture
Fractures within skin that keep overlying skin intact
Compound fractures
Bone fracture that pierces skin and communicates directly with skin surface
Comminuted fractures
Bone fractures that cause bone to be fragmented
Displaced fracture
Bone fracture in which the ends of bones at the fracture site do not align.
- need to be surgically put in place.
Stress fracture
Bone fractures that are slow developing fractures that follow increased physical activity and repetitive loads of stress.
Green stick fractures
Bone fractures that extend incompletely through the bone (often resembling twisting a green health tree branch)
- most commonly seen in soft bones (especially infants)
Pathogenic fracture
Bone fracture caused by weakened bone by an underlying disease process
Osteonecrosis
Infarction of bone and bone marrow.
- occurs in medullary cavity and can directly affect cortex or medulla.
Most commonly caused by bone fractures or corticosteroids
Vascular insufficiency causes
Injury to blood vessels
Thromboembolism
External pressure on veins
Venous occlusion
Osteonecrosis morphology
Yellow often edge shaped empty lacunae with necrotic adipocytes.
- creates insoluble soaps in the bone
- subcontractors infants in tandem also causes collapse of necrotic bone.
Clinical signs of osteonecrosis
Pain associated with activity and eventually becomes constant.
Often osteoarthritis occurs after osteonecrosis.
A lot of osteonecrosis is clinically silent.
Osteomyelitis
Inflammation of bone and marrow
- always secondary to primary infection in the bone.
All microorganisms can cause this infection, however mycobacterium and pyogenic bacteria are the most common.
- especially potent in immunosuppressive population
Pyogenic osteomyelitis infections
Arise at bone via
- hemagoenous spread
- direct implantation
- in adults usually occurs via open fractures and diabetic infections of feet.
- S. Aureus is the most common bacteria. (80-90%)
Other possible pyogenic osteomyelitis infections
E. coli, klebsiella, Pseudomonas in adults
Neonates: haemophilus influenza and B strep.
Sickle cell patients: salmonella
Sites of pyogenic osteomyelitis
Infants: frequent infection in metaphysis or epiphysis of long bones.
Children: metaphysis infections most common
Adults epiphyses and subchondral regions most common.
Pyogenic osteomyelitis morphology
Three stages: acute, subacute, chronic
- Dead bone = sequestrum*
- new bone = involucrum*
Acute pyogenic osteomyelitis morphology
Proliferation, neutrophilic inflammation and necrosis within 48 hrs.
Mycobacterium osteomyelitis
Most common in immunosuppressive population and can occur in TB patients.
- histologically shows caseous necrosis of bone and granulomas.
- more destructive and harder to control than pyogenic osteomyelitis
Skeletal syphilis
Syphilis and yaws infections that tend to occur in Endochondral ossification and periosteum areas.
Causes areas of bone to not fuse properly and can leave holes upon xrays/CTs
Brachydactyly types D and E affected gene
HOXD13
Achondroplasia and thanatophoric dysplasia gene affected
FGFR3
Both are related to limb shortening and bowing or bones
