Aggressive vs. Non-Aggressive Bone Lesions

Question 1

How are the 6 Roentgen signs used for assessing bone disease?

Answer 1

1. LOCATION - metaphyseal, diaphyseal, physeal, epiphyseal, proximity to nutritional foramen, centered on joint
2. SIZE
3. SHAPE - lysis, proliferation, amorphous, definition
4. MARGINS - irregular vs regular, ill-defined vs defined proliferation/lysis
5. NUMBER - polyostoic, monostotic, amount of lesions
6. OPACITY

Question 2

How do the patterns of lysis compare in non- aggressive and aggressive bone lesions?

Answer 2

NON-AGGRESSIVE = geographic

AGGRESSIVE = moth-eaten, permeative

Question 3

How do periosteal reactions compare in non- aggressive and aggressive bone lesions?

Answer 3

NON-AGGRESSIVE = smooth, well-defined, continuous

AGGRESSIVE = irregular, ill-defined, interrupted

Question 4

How does the zone of transition compare in non- aggressive and aggressive bone lesions?

Answer 4

NON-AGGRESSIVE = narrow, well-defined

AGGRESSIVE = broad, ill-defined

Question 5

How does the rate of change compare in non-aggressive and aggressive bone lesions?

Answer 5

NON-AGGRESSIVE = slow

AGGRESSIVE = fast

Question 6

How does cortical destruction compare in non- aggressive and aggressive bone lesions?

Answer 6

NON-AGGRESSIVE = not as typical

AGGRESSIVE = common

Question 7

What is geographic lysis?

Answer 7

an indicator of non-aggressive bone lesions where there is a well-defined region of lysis with regular borders and short zones of transition

(open physis = young patient, irregular stifle joint)

Question 8

What is moth-eaten lysis?

Answer 8

an indicator of aggressive bone lesions where there are multiple, irregular, and ill-defined regions of lysis that coalesce to form larger regions

(periosteal reaction also seen)

Question 9

What is permeative lysis?

Answer 9

an indicator of aggressive bone lesions where there are smaller, pinpoint, coalescing regions of lysis that are more ill-defined than moth-eaten and have a broader zone of transition

Question 10

What is the periosteum? How long does it take to develop?

Answer 10

specialized connective tissue that covers all bones and possessed bone-forming potential (not typically visualized, unless it is mineralized)

7 days after injury

Question 11

Periosteal reactions:

Answer 11

• continuous, smooth, well-defined = non-aggressive
• interrupted, irregular, ill-defined = aggressive

Question 12

What is Codman’s triangle?

Answer 12

disruption of cortical regions of bone with elevation due to aggressive processes

Question 13

What is the most common cause of non-aggressive periosteal reactions?

Answer 13

callus associated with healed/healing fractures

• smooth, continuous, well-defined

Question 14

What kind of periosteal reaction is associated with low grade or chronic osteomyelitis?

Answer 14

smooth and continuous, but more ill-defined

• assess lymph nodes and swelling

Question 15

Periosteal reaction:

Answer 15

smooth, continuous, irregular, well-defined

• yellow = not as smooth, well-defined
• green = disrupted periosteum

Question 16

What do irregular and interrupted periosteal reactions indicate? What are the most common appearances?

Answer 16

more aggressive lesions

• columnar
• spiculated
• sunburst
• amorphous

Question 17

Why is the cortical lysis commonly caused by aggressive bone lesions especially important?

Answer 17

can lead to pathological fractures

Question 18

What is the zone of transition? How are they different in non-aggressive and aggressive lesions?

Answer 18

distance between normal and abnormal bone in a lesion

• sharp/well-defined/short = slowly progressing = non-aggressive
• indistinct/ill-defined/long = rapidly expanding = aggressive

Question 19

Zone of transition:

Answer 19

Question 20

What is a polyostotic lesion? What are 2 common causes?

Answer 20

aggressive lesion affecting more than one bone

1. hematogenous/lymphatic spread of metastasis or systemic infection
2. metabolic/nutritional disease

Question 21

What 2 disorders should be considered if there are polyostotic lesions centered on a joint?

Answer 21

1. joint-centric neoplasia —> synovial cell sarcoma, histiocytic sarcoma
2. septic/immune-mediated arthritis

Question 22

What is a monostotic lesion? What do features of aggression and non-aggression suggest?

Answer 22

lesion affecting only one bone

• AGGRESSION = primary bone neoplasia, fungal or bacterial osteomyelitis
• NON-AGGRESSIVE = bone infarction, fracture remodelling, bone cyst

Question 23

How do aggressive and benign lesions compare in rate of change? What can be done to differentiate?

Answer 23

• AGGRESSIVE = change rapidly
• NON-AGGRESSIVE = change slowly, with minimal alterations in 7-14 day periods

take second radiographs within 7-14 days

Question 24

What 3 parts of the DAMNITV scheme are most commonly associated with aggressive bone lesions?

Answer 24

1. AUTOIMMUNE - immune-mediated arthropathy (rheymatoid arthritis)
2. NEOPLASIA - primary bone tumor (metaphyseal), metastatic (polyostotic, near nutrient foramen), joint-centric neoplasia
3. INFECTION - bacteria, fungal

Question 25

Generating a differential diagnosis for aggressive bone lesions:

Answer 25

Question 26

Match the descriptors to the appropriate type of bone lesions: - regional or pulmonary metastases common - does not metastasize - sharp, well-defined lesion margins - moth-eaten lysis - enchondroma - osteosarcoma - no lysis of surrounding bone - moderate to severe soft tissue swelling - geographic lysis - not associated with pathological fractures - associated with pathological fractures - smoothly marginated periosteal reaction - irregular, ill-defined lesion margins - permeative lysis - short zone of transition - large zone of transition - irregular, ill-defined periosteal reaction or osteoproliferation - related to trauma

Answer 26

AGGRESSIVE - metastasis, moth-eaten lysis, osteosarcoma, moderate to severe soft tissue swelling, associated with pathological fractures, ill-defined lesion margins, permeative lysis, long zone of transition, ill-defined periosteal reaction or osteoproliferation NON-AGGRESSIVE - no metastasis, sharp and well-defined lesion margins, enchondroma, no lysis, geographic lysis, not associated with pathological fractures, smoothly marginated periosteal reaction, short zone of transition, related to trauma

Question 27

How many radiograpic features of aggression must be present to conclude the lesion you are describing is aggressive?

Answer 27

1 ---> very conservative

Question 28

Attached are lateral and craniocaudal images of a 10 year old Labrador retriever with progressive lameness and muscle atrophy involving the right pelvic limb. Based on the assessment of the distal tibial lesion, select five features present. a. irregular, ill-defined, interrupted periosteal reaction b. smooth, well-defined, continuous periosteal reaction c. permeative lysis d. long, ill-defined zone of transition e. short, well-defined zone of transition f. cortical disruption g. geographic lysis h. severe soft tissue swelling

Answer 28

A, C, D, F, H

Question 29

This lesion is centered on which region of bone? a. diaphysis b. metaphysis c. epiphysis

Answer 29

B ---> distal tibial metaphysis

Question 30

For this lesion, which differential diagnosis would you most likely select as your top differential? a. septic arthritis b. primary osseous neoplasia c. osteomyelitis d. bone cyst

Answer 30

B ---> aggressive, distal tibia, Hx (10 y/o Lab)

Question 31

What is the most common primary bone neoplasm in dogs?

Answer 31

osteosarcoma

Question 32

What is the general distribution of osteosarcomas? What are the 5 most common regions it is found?

Answer 32

"away from the elbow, toward the knee" 1. distal radius/ulna 2. distal femur 3. proximal tibia 4. scapula 5. proximal humerus

Question 33

In what region of the bone is osteosarcoma most commonly found? Metastatic lesions?

Answer 33

PRIMARY = metaphyseal region METASTATIC = diaphyseal, reflecting location of the vasculature channel and portal of entry into the bone

Question 34

How is the age distribution of osteosarcoma unique?

Answer 34

BIMODAL ----> frequency spikes at 2 years of age and geriatric patients