Bone non-neoplastic diseases Flashcards
what are the non-neoplastic disorders found in bone?
1) congenital
2) osteoclasts dysfunction
3) osteonecrosis
4) metabolic bone diseases
5) infections
6) fractures
7) miscellaneous
what are the congenital disorders of bones?
1) osteogenesis imperfecta 2) achondroplasia 3) osteopetrosis
what is another name for osteogenesis imperfecta?
brittle bone disease (fragilitas ossium)
what is osteogenesis imperfecta?
defective synthesis of type 1 collagen by mutations in alpha 1 and 2 chains of collagen
what will you find in osteogenesis imperfecta?
a lot of fractures blue sclera deafness
what is achondroplasia?
impared formation of long bones and of cartilage at growth plate
where is the mutation in achondroplasia?
FGFR3
is the mutation dominant or recessive?
dominant
what is happening at the molecular level in achondroplasia?
overexpression of FGFR3 causes inhibition of cartilage synthesis in growth plate reducing the growth of long bones
what are the clinical findings of achondroplasia?
short extremities poor endochondrial bone formation
is the intramembranous bone affected in achondroplasia?
no
what is another name for osteopetrosis?
marble bone disease
what is osteopetrosis?
group of bone diseases that have decreased osteoclast function
what will osteopetrosis show in a lab?
greatly increased bone resorption
what characterizes the pathology of osteopetrosis?
• Bones becomes dense, thick • Marrow cavity replaced by bone • The thickened bones are brittle and fracture easily.
what is the most common defect found in osteopetrosis?
carbonic anhydrase 2 mutation causing loss of acidic environment
what are the 3 stages of Paget’s disease?
- Osteolytic stage
- Mixed osteolytic-osteoblastic stage
- Osteosclerotic - thick, sclerotic bone that breaks easy
what are the clinical findings in osteopetrosis?
- Pancytopenia
- Leukoerythroblastic blood (in histology)
- Extramedullary hematopoiesis = hepatosplenomegaly
- Cranial nerve compression = by narrowing of cranial foramina
- Hydrocephalus
what are the clinical findings in paget’s disease?
- Bone pain
- Increasing hat size*
- Hearing loss:*
- Lion like facies
- Skeletal deformities* = tibial bowing
- Elevated alkaline phosphatase*
- Increased risk of osteogenic sarcoma*
- High output cardiac failure = due to AV connections in vascular bone
what is another name for paget’s disease?
paget’s disease is characterized by episodes of?
osteitis deformans
Excessive and disordered bone resorption by osteoclasts followed by exuberant but disorganized bone formation
pagets disease can involve 1 bone or many bones…how do you call these types of involvement?
what common bones are involved?
Monostotic: involving one bone
Polystotic : involving multiple bones.
pelvis>skul>femur
what do you see in the osteolytic stage of paget’s disease?
osteoclastic resorption of bone predominates
what do you see in the osteolytic and osteoblastic stage of paget’s disease?
Osteolytic and increased osteoblastic bone formation
formation of new bone: soft/weak and little mineralization
- the deposition is in mosaic formation (like tiles)
- look for increased alkaline phosphatase levels
what is the treatment for paget’s disease?
calcitonin: inhibits osteoclast function
biphosphonates: induces apoptosis of osteoclasts
what is osteonecrosis?
Ischemic infarction of bone & bone marrow.
what causes ischemia leading to osteonecrosis?
- Vascular interruption (fracture like the femoral neck)
- Corticosteroids*
- Alcoholism
- Sickle cell disease or Caisson disease.
what are the most common sites of osteonecrosis?
femoral head
scaphoid bone
what is a Medullary infarct?
infarct that involves marrow and the cancellous bone
(clinically silent)
what is a Subchondral infarct?
Wedge shaped area of necrosis with viable overlying articular cartilage leads to chronic pain
what is caisson disease?
an air embolism that goes into the bone
