Brant And Helms Ch 46

Front 1

Myositis ossificans is differentiated from osteogenic sarcoma by?

Back 1

both look like calcified fluffy lesions but myositis ossificans has a circumferential nature.

Front 2

If it is hard to tell if a lesion looking like myositis offisficans is circumferential what do you do?

Back 2

CT or delayed repeat films 1 or 2 weeks

Front 3

What can you do to determine if a lesion is an avulsion injury vs malignancy? (2)

Back 3

Repeat films in several weeks. Also location is helpful (at ligament and tendon insertion sites)

Hint 3

two things...one is a finding

Front 4

What is a cortical desmoid?

Back 4

a process on the medial supracondylar ridge of the distal femur that is considered to be an avulsion of adductor magnus muscle. It can simulate an aggresive lesion.

Front 5

1. What is the characteristic radiographic findings of cortical desmoid?
2. What are other findings (history, p.e.)?

Back 5

1. Occur only at the posteromedial epicondyle of the femur, might or might not have periosteal reaction, have increased radionuclide uptake on bone scan, Often found as incidental findings on MR of knee and have characteristic appearance.
2. might or might not be assoc with pain which should go away at rest. usually occur in young people.

Hint 5

1. three things
2. three things

Front 6

What is the MR appearance of a cortical desmoid that is characteristic?

Back 6

faint lytic leasion in the medial aspect of the distal femur more specifically in the medial supracondylar ridge.

Front 7

Trauma lesion mimicking malignancy? (3 examples)

Back 7

1. Geode's. biopsy does not, in this case, look like malignancy histologically. However this shouldn't occur because geode's always come with other radiographic findings that give away that it is benign (oa findings OR other instances having geode's such as ra, avn, CPPD - calcium pyrophosphate dihydrate deposition dz)
2. Fracture that is not immobilized can have extensive periostitis and osteosclerosis (lack of immobilization creates an exuberant callus)
3. Pseudo-dislocation of the humerus (from fracture and hemarthrosis causing inferior sublux but not dislocation)

Hint 7

Three of them.

Front 8

Focal sclerosis of vertebrae in the region of the endplate in the setting of disk space narrowing and osteophytosis is what?

Back 8

Discogenic Vertebral Sclerosis...should not be boipsied

Front 9

Typical clinical setting of discogenic vertebral sclerosis?

Back 9

Middle aged woman with chronic back pain

Front 10

What can help in proving a vertebral sclerotic lesion is discogenic vertebral sclerosis?

Back 10

clinical history, old films, and typical radiographic findings

Front 11

Normal variants that can mimic aggressive lesions... (3 examples)

Back 11

1. dorsal defect of the patella
2. pseudocyst of the humerus
3. os odontoideum

Hint 11

arm, knee, neck

Front 12

Dorsal defect of the patella...describe it and what three things does it mimic?

Back 12

"upper outer quadrant" lytic lesion. It can mimic focus of infection, osteochondritis dissecans or chondroblastoma

Front 13

Pseudocyst of the humerus...describe and what three example things can it mimic?

Back 13

area of increased cancellous bone in the region of the greater tuberosity of the humerus giving it more lucent appearance. Can mimic infection, chondroblastoma or mets.

Front 14

What can occur to a pseudocyst of the humerus to trigger biopsy and excision?

Back 14

hyperemia and increased uptake on bone scan secondary to a rotator cuff injury...biopsy looks like aggressive lesion.

Front 15

Os odontoideum...what is it and what are the findings?

Back 15

1. Non-union of dens to rest of C2. 2. Anterior sublux of C1 on flexion,
3. no neuro sx,
4. well corticated dens fragment,
5. hypertrophied, densely corticated anterior arch of C1.

Front 16

Why is recognizing Os odontoideum important for the radiologist.

Back 16

This is not an emergency and can be fixed electively...saved patient from the halo.

Front 17

List 4 "obviously benign (don't touch) lesions"

Back 17

NOF
Bone island
Unicameral bone cyst
Bone infarction

Front 18

Non ossifying fibroma (NOF) vs fibrous cortical defect.

Back 18

Same thing only NOF's are >2cm.

Front 19

Describe findings of an NOF? (location, rad appearance)

Back 19

1. lytic lesion in cortex of metaphysis of a long bone
2. well defined, often sclerotic, scalloped border
3. slight cortical expansion.

Front 20

What age group do you find NOF's?

Back 20

<30...natural history is involution/fill with new bone = sclerotic appearance after 30 and increased radionuclide activity.

Front 21

What are NOF's mostly mistaken for?

Back 21

infection, EG,fibrous dysplasia, abc.

Front 22

Can NOF's degenerate into malignancy?

Back 22

negative

Front 23

Do surgeon's advocate prophylactic curettage of NOF's?

Back 23

No..this is unlike unicameral bone cysts.

Front 24

Bone islands usual size...

Back 24

1cm or smaller...but occasionally they grow to golf ball size or larger.

Front 25

What can large bone islands mimic? List one way to differentiate them on physical exam.

Back 25

Sclerotic mets...but they are always asymptomatic.

Front 26

Two ways to distinguish large bone island radiographically...

Back 26

1. usually oblong with long axis in the axis of stress on the bone
2. margins when examined closely show bony trabeculae extending from the lesion into the normal bone in a spiculated fashion

Front 27

Unicameral bone cyst...how do you treat?

Back 27

often prophylactically curettaged and packed to prevent fracture unless in the calcaneus.

Front 28

Why aren't unicameral bone cysts curettaged when in the calcaneus?

Back 28

they are always anteroinferior where there is little stress.

Front 29

Radiographic characteristics of unicameral bone cysts...(6 but 3 classic B and H)

Back 29

1. ALWAYS central (only FEGNOMASHIC lesion that is always central)
3. One of the few lesions that does not occur most commonly around the knees. Can occur in any bone. Common site calcaneus. 2/3 to 3/4 occur in proximal humerus and femur.
4. Fallen fragment sign (post fracture)
5. Begin at physeal plate in long bones and grow into shaft. Can later grow into epiphysis but usually wont.
5. No periositis
6. Must be younger than 30.

Front 30

Other names for unicameral bone cyst? three

Back 30

simple bone cyst or solitary bone cyst are the same thing. unicameral = one compartment.

Front 31

Radiographic appearance of bone infarcts...(2)

Back 31

1. Early on they are patchy or mixed lytic-sclerotic pattern
2. Can also even have a permeative look...scary because looks like aggressive lesion then.

Front 32

Bone infarction....how can you differentiate from aggressive lesions?

Back 32

1. multiple
2. diametaphyseal region of long bone
3. underlying disorder
4. MR

Front 33

What does one see on MR with bone infarcts?

Back 33

characteristic serpiginous border.

Front 34

What underlying disorders would make you think of bone infarct? (2)

Back 34

sickle cell, SLE

Front 35

Where do you commonly get pseudo-cysts and why?

Back 35

Pseudocysts are in areas of low stress...anteroinferior calcaneus...(this is also where you get unicameral bone cysts commonly), and humerus greater troch.