Chapter 18 Flashcards
one sentence summary of achondroplasia
- Defect in proliferation of chondrocytes at the cartilage growth plate
- Overexpression of FGFR3 inhibits growth.
why is there blue sclera in osteogenesis imperfecta?
Blue sclera- Thinning of scleral collagen reveals underlying choroidal vein
what is osteopetrosis? what is the enzyme defect?
Inherited defect of bone resorption resulting in abnormally thick, heavy bone that fractures easily –> Due to poor osteoclast function
Multiple genetic variants exist; carbonic anhydrase II mutation leads to loss of the acidic microenvironment required for bone resorption.
what are the complications of osteopetrosis?
- Bone fractures
- Anemia, thrombocytopenia, and leukopenia with extramedullary
hematopoiesis- due to bony replacement of the marrow - Vision and hearing impairment-due to impingement on cranial nerves
- Hydrocephalus-due to narrowing of the foramen magnum
- Renal tubular acidosis- seen with carbonic anhydrase II mutation
i. Lack of carbonic anhydrase results in decreased tubular reabsorption of HCo,-, leading to metabolic acidosis.
What is the one sentence summary of osteomalacia/rickets?
Osteoblasts normally produce osteoid, which is then mineralized with calcium and phosphate to form bone.
Due to low levels of vitamin D,
lab values of osteomalacia/rickets?
Laboratory findings include decreased serum calcium and phosphate, increased PTH, and INCREASED alkaline phosphatase.
stages of pagets disease of bone
Three distinct stages are (l) osteoclastic, (2) mixed osteoblastic-osteoclastic, and (3)
osteoblastic.
1. End result is thick, sclerotic bone that fractures easily.
2. Biopsy reveals a mosaic pattern oflamellar bone (Fig. 18.2).
clinical features of pagets disease of bone
Clinical features
- Bone pain- due to microfractures
- Increasing hat size- Skull is commonly affected.
- Hearing loss-impingement on cranial nerve
- Lion-likefacies- involvementofcraniofacialbones
labs of pagets disease of bone
Isolated elevated alkaline phosphatase-most common cause of isolated elevated
alkaline phosphatase in patients> 40 years old
complications of pagets disease of bone
l. High-output cardiac failure-due to formation of AV shunts in bone 2. Osteosarcoma BECAUSE THERE ARE SOME MANY BLASTS REPLICATING AND LOOKY THERE A TUMOR OF THE BLASTS
Transient bacteremia (children) seeds metaphysis. Open-wound bacteremia (adults) seeds epiphysis.
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what are the histological features of OA?
Pathologic features include
l. Disruption of the cartilage that lines the articular surface (Fig. 18.7); fragments ofcartilage floating in the joint space are called ‘joint mice.’
2. Eburnation of the subchondral bone
3. Osteophy te formation (reactive bony outgrowths); classically arises in the DIP
(Heberden nodes) and PIP (Bouchard nodes) joints of the fingers
What part of the fingers can OA effect?
DIP and PIP
Osteophy te formation (reactive bony outgrowths); classically arises in the DIP
(Heberden nodes) and PIP (Bouchard nodes) joints of the fingers
what is the pathological hallmark of RA?
Hallmark is synovitis leading to formation of a pannus (inflamed granulation tissue).
2. Leads to destruction of cartilage and ankylosis (fusion) of the joint
what joints are affected in RA?
Symmetric involvement of PIP joints of the fingers (swan-neck deformity),
wrists (ulnar deviation), elbows, ankles, and knees is characteristic (Fig.
18.8); DIP is usually spared (unlike osteoarthritis).
