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Core > MSK: Agressive Lesions > Flashcards

MSK: Agressive Lesions Flashcards

1
Q

What are the most common primary osseous malignancies?

A
  • Myeloma/plasmacytoma (27%)
  • Osteosarcoma (20%)
  • Chondrosarcoma (20%)
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2
Q

What is the best sign that an osseous lesion is aggressive?

A

A wide zone of transition (you can’t trace the edges of the lesion with a pencil)

Note: This indicates that the lesion is too fast for the bone to be able to create a sclerotic border around it.

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3
Q

Arrow

A

Codman triangle, indicating a very aggressive lesion

Note: The lesion grew so fast it burst out of the cortex, leaving the Codman triangle pushed away.

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4
Q

Arrow

A

Codman triangle, indicating that this is a Pathologic fracture due to a very aggressive lesion

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5
Q

What are the major subtypes of osteosarcoma?

A
  • Intramedullary (85%)
  • Parosteal (4%)
  • Periosteal (1%)
  • Telangiectatic (rare)
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6
Q

Common etiologies for osteosarcoma

A
  • Idiopathic (most common)
  • Radiation therapy
  • Pagets
  • Infarctions
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7
Q

Osteosarcoma is more common in what pt population?

A

Young pts (10-20 years)

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8
Q

What are the most common locations for osteosarcoma?

A
  • Femur (40%)
  • Proximal tibia (15%)
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9
Q

What type of periosteal reactions are suspicious for osteosarcoma?

A
  • Subburst
  • Lamellated
  • Codman triangle
  • Reverse zoning phenomenon
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10
Q

What is the classic cause of occult pneumothorax?

A

Osteosarcoma metastasis to the lung

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11
Q
A

Think osteosarcoma

Note: Sunburst periosteal reaction in the femur.

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12
Q

Why is it important to image the entire bone that contains an osteosarcoma?

A

Skip metastases occur in 5% of cases (usually proximal to the primary tumor)

Note: A bone scan is usually done during staging also for this reason.

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13
Q

What imaging studies are usually performed during osteosarcoma staging?

A
  • Bone scan (monoostotic vs polyostotic)
  • Chest CT (to look for lung mets)
  • MRI of the entire involved bone (to look for skip lesions and plan biopsy)
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14
Q

When does osteosarcoma recurrence usually occur?

A

Within 2 years of surgical resection

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15
Q

What is the most common location for osteosarcoma relapse?

A

Lung (80%)

Note: Bone relapse occurs less frequently (20%).

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16
Q

Why is a second biopsy usually done following Neoadjuvant chemotherapy for osteosarcoma?

A

To predict outcome

Note: 90% tumor death is a good prognostic feature.

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17
Q

What is the classic location for a parosteal osteosarcoma?

A

Posterior distal femur metaphysis

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18
Q
A

Think parosteal osteosarcoma

Note: Posterior distal femur metaphysis is a common location.

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19
Q

Reverse zoning phenomenon…

A

Think osteosarcoma

Note: This is when you have soft tissue calcification with a denser matrix in the center and less dense matrix peripherally (the opposite of myositis ossificans).

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20
Q

Are parosteal osteosarcomas usually lower or higher grade?

A

Low grade (typically the lowest grade of all the subtypes of osteosarcoma)

21
Q

Arrows

A

String sign, suspicious for parosteal osteosarcoma

Note: The radiolucent string separates the bulky tumor from the cortex.

22
Q

List the major subtypes of osteosarcoma from best prognosis to worst prognosis

A
23
Q

What is the classic location for a periosteal osteosarcoma?

A

Medial distal femur diaphysis

24
Q
A

Think periosteal osteosarcoma

Note: Broad-based cortically attached tumor with aggressive, lamellated/Codman’s triangle periosteal reaction and associated partially mineralized soft tissue mass.

25
Q

What are the two subtypes of surface osteosarcoma?

A
  • ParOsteal (Outer layer of periosteum)
  • PerIosteal (Inner layer of periosteum)
26
Q

Which subtype of surface osteosarcoma often has marrow extension?

A

Parosteal (50%)

Note: Periosteal osteosarcomas usually do not have marrow extension.

27
Q

What is the classic imaging finding for telangiectatic osteosarcoma?

A

Fluid-fluid levels

28
Q

Differential for osseous lesion with fluid-fluid levels

A
  • Telangiectatic osteosarcoma
  • Aneurysmal bone cyst
  • Giant cell tumor

Note: Telangiectatic osteosarcoma should be more nodular and enhancing than the others.

29
Q

Permeative lesion in the diaphysis of a pediatric pt…

A

Think Ewings sarcoma

Note: Infection and eosinophilic granuloma can also look like this.

30
Q

Where do Ewing sarcomas usually metastasize to?

A
  • Bone (most common, often to the spine)
  • Lung

Note: Ewings is the most likely sarcoma to metastasize to another bone (often appears polyostotic).

31
Q

Is it common to have a soft tissue component in Ewings sarcoma?

A

Yes (80%), most commonly to the spine

Note: Unlike for osteosarcoma, the soft tissue component rarely has calcification.

32
Q

What is the most common location for Ewings sarcoma?

A

Femoral diaphysis

33
Q

Pediatric pt

A

Think Ewing sarcoma

Note: Permeative/moth-eaten lesion in the femoral diaphysis of a pediatric pt.

34
Q

Ewings sarcoma is more common in what pt population?

A

Pediatric (~15 y/o)

35
Q

Chondrosarcoma is usually seen in what pts?

A

Older adult males (40-70 y/o)

36
Q

What is the most common location for chondrosarcoma?

A

Distal femur

Note: Chondrosarcoma is more common in proximal tubular bones and limb girdles (e.g. triradiate cartilage in pelvis) due to more abundant cartilage.

37
Q

What is the most common location for chondrosarcoma metastases?

A

Lung

Note: Bone is second most common.

38
Q

Chondroblastoma in an adult…

A

Think clear cell chondrosarcoma

39
Q

What are the main aggressive osseous lesions?

A
  • Osteosarcoma
  • Ewings sarcoma
  • Chondrosarcoma
  • Chordoma
40
Q

Risk factors for chondrosarcoma

A
  • Pagets
  • Cartilaginous disorders (e.g. osteochondromas, Maffucci, etc.)
41
Q

What type of matrix does this tumor have?

A

Chondroid

Note: Rings and arcs.

42
Q

What features should make you suspicious of a chondrosarcoma rather than an enchondroma?

A
  • Pain
  • Cortical destruction
  • Scalloping of > 2/3 of the cortex
  • Size > 5cm
  • Changing matrix
43
Q

What is the typical age group for chordomas?

A

30-60 y/o

44
Q

What is the most common location for a chordoma?

A
  • Sacrum (most common)
  • Clivus
  • Vertebral body
45
Q

What is the classic imaging feature of a chordoma?

A

Very T2 bright

46
Q

Chordomas can be seen in different locations, but they will ALWAYS be…

A

Midline

Note: This is because it derived from a notochord remnant.

47
Q

What is the most common primary malignancy of the spine?

A

Chordoma

48
Q

What is the most common primary malignancy of the sacrum?

A

Chordoma

49
Q

What is the most common spinal location for a chordoma?

A

C2

Core (98 decks)

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