(3) Hematologic Disorders Flashcards
Sickle cell anemia involves a structural deformity of ____
hemoglobin
Thalassemia is a disorder of ____
hemoglobin synthesis
What is hemophilia?
Deficiency of clotting factors
Sickle cell and thalassemia are ____ anemias resulting in bone disorders.
Hemolytic
What are the effects of sickle cell anemia and thalassemia on bone?
- marrow hyperplasia
- growth disturbances (shorter bones)
What are the radiographic findings of sickle cell anemia and thalassemia?
- osteopenia from birth
- osteonecrosis (SC>)
- “H-shaped” vertebra (SC>)
- hair on end appearance of skull (T>)
- Erlenmeyer flask deformity (T>)
What radiographic findings are specific to sickle cell anemia?
- osteonecrosis
- H-shaped vertebra
What radiographic findings are specific to thalassemia?
- hair on end appearance of skull
- Erlenmeyer flask deformity
How does an H-shaped vertebra compare to Schmorl nodes?
Bigger than Schmorl nodes
How does an H-shaped vertebra compare to nuclear impressions?
Sharper than nuclear impressions
What causes the hair on end appearance seen in thalassemia?
Marrow hyperplasia
(inner/outer table space fills w/ red marrow to ^RBCs, spreading inner & outer tables)
What are the clinical characteristics of hemophilia?
- ^bleeding (^risk of hemorrhage, ^bruising)
- M>F
- repetitive hemarthroses —> deformities & arthropathy
What are the imaging features of hemophilia?
- osteopenia
- growth abnormalities (ballooning of epiphyses d/t early fusion of 2° oss. centers)
- arthropathy
- hemophiliac pseudotumors (geo. lytic)
What are the imaging features specific to hemophilic arthropathy?
- bloody jt effusions
- synovitis, pannus
- cartilage degeneration (OA)
- wide intercondylar notch
- squaring of patella
- predisposed to myositis ossificans
What is a differential diagnosis for ballooning of epiphyses seen in hemophilia?
JIA
What joint is most commonly affected by hemophilic arthropathy?
Knee
What are the 2 main subcategories of osteonecrosis?
- avascular necrosis (AVN)
- bone infarct
What part of bones is primarily affected by AVN?
Epiphysis
What part of bones is primarily affected by bone infarct?
- metaphysis
- diaphysis
What are 3 possible causes of osteonecrosis?
significant reduction/obliteration of blood supply to bone:
- arterial rupture (trauma)
- arterial blockage (thrombus, emboli, vasculitis)
- arterial compression (myeloproliferation)
What is the mnemonic for the etiologic risk factors of osteonecrosis?
- Pancreatitis, Pregnancy
- Lupus
- Alcoholism
- Steroids (corticosteroids)
- Trauma
- Idiopathic, Infection
- Caisson Dz (the Bends), Collagen vasc Dz, Cushing Dz
- Rheumatoid arthritis, Radiation therapy
- Amyloidosis
- Gaucher Dz
- Sickle cell Dz/thalassemia
What are the clinical features of osteonecrosis?
- location & etiology dependent
- insidious onset
- pain, antalgia, painful ROM, muscle atrophy
Describe the typical pain of AVN.
joint pain
Describe the typical pain of bone infarct.
bone pain
What is the radiographic latent period of osteonecrosis?
few weeks to 1 yr
(if normal xrays w/ any PLASTIC RAGS risk factor, get MRI)
What are the 4 phases of avascular necrosis?
- avascular
- revascularization
- repair & remodeling
- deformity
What are the imaging findings associated with the avascular phase of AVN?
- ^jt space
- capsular swelling
- appears same as normal bone radiographically
What are the imaging findings associated with the revascularization phase of AVN?
- sclerosis (snowcapping)
- flattening/collapse of articular surface
- fragmentation
- subchondral cysts
- subchondral Fx (crescent sign)
What is “snowcapping” as seen in AVN?
sclerosis:
weak new bone formation on top of dead bone
What radiographic sign is indicative of a subchondral fracture due to AVN?
crescent sign
(lucency under articular surface)
What are the imaging findings associated with the repair & remodeling phase of AVN?
no distinct findings
What are the imaging findings associated with the deformity phase of AVN?
secondary DJD
What are the imaging findings associated with bone infarct?
- does not weaken bone (rarely deformity/fracture)
- stippled medullary calcification (occasionally serpiginous contour)
If bone infarct undergoes malignant degeneration, what does it become?
fibrosarcoma
Give 3 differentials in order of most to least likely for stippled calcification of a long bone in a patient over 40 years of age.
- Chondrosarcoma
- Infarct
- Enchondroma
Give 3 differentials in order of most to least likely for stippled calcification of a long bone with a serpiginous contour.
- Infarct
- Enchondroma
- Chondrosarcoma
Give 3 differentials in order of most to least likely for stippled calcification of a long bone in a patient with sickle cell anemia.
- Infarct (PLASTIC RAGS risk factor)
- Enchondroma
- Chondrosarcoma
