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40 Cards in this Set

  • Front
  • Back
Are malignant bone tumors common?
thankfully no
What two "benign" conditions mimic malignant bone lesions...
infection and EG
What four conditions are given in standard text to differentiate malignant vs benign bone lesions?
1. cortical destruction
2. periostitis
3. orientation or axis of the lesion
4. zone of transition
Descriptive terms for malignant periostitis...
onion skin, amorphous or sunburst like.
Benign periostitis looks...
dense like callous of a bone....because it happens slower and has time to lay down more bone.
Many benign lesions cause malignant looking periostitis so this isn't the greatest criteria....list some..
EG, infection, trauma, osteoid osteoma, ABC all can...
Detection of benign periostitis is more/less helpful than that of malignant....
more helpful because malignant lesions wont cause benign periostitis unless there is concommitant fracture or infection. it is dense, wavy, thick.
What does axis have to do with malignant characterization?
Doesnt help much. It is said that if it grows with the axis it is most likely benign....too many exceptions.
Most reliable plain film indicator for malignancy?
Wide zone of transition.
If a lesion has a wide zone of transition it can be said to be what?
Aggressive but not necessarily malignant.
Examples of benign lesions with a wide zone of transition.
infection, EG
Examples of lesions having permeative border....also a type of wide zone of transition...
MM, reticulum cell sarcoma (primary lymphoma of bone), Ewing sarc are typical. Sometimes infection and EG.
Differential of malignant bone lesions is long/short?
What makes pinning a malignancy on bone lesions fairly easy?
short differential and strict age categories.
Bone malignancies age 1-30...
Ewing sarc, orteogenic sarc.
Malignant bone lesions age 30-40...
giant cell tumor, parosteal ssarcoma, fibrosarcoma, malignant fibrous histiocytoma, primary lymphoma of bone.
Malignant bone lesions age greater than 40...
chondrosarcoma, metastatic dz, myeloma
Plain film is best for _______and MR is used for_____in malignant bone lesions.
Plain film dianosing. MR finding out extent both in skeleton and in soft tissues. If resection is contemplated MR should be performed.
MR criteria for malignancy...
irregular mass that can encase neurovascular structures or invade bone.
Intensity on T1 and T2 with tumors?
low T1 very high T2. there are a few exceptions (fibrosarc, malignant fibrous histiocytoma, desmoid occasionally all show low T2)
List a few lesions (benign) better diagnosed on MR....
lipomas, hemangiomas, avm's
Gad should be administered to differentiate what from a tumor?
fluid collection (effusion or bursa will have rim enhancement vs full enhancement with tumor)
Most common malignant primary bone tumor?
Characteristics of osteosarcs....
lots of times they are on ends of long bones but not always so not a good discriminator; destructive or lytic; many different types and classifications exist but radiologist neednt know them.
What on MR helps diagnose an osteosarc?
large soft tissue component with heterogenous high and low signal on both T1 and T2.
Parosteal osteosarcoma...what is important to know?
Radiologist plays an important role in deciding treatment. if it hasn't invaded into medullary region of bone it is shaved off. If it does it is treated like a central osteosarcoma as it is considered to be just as aggresive. MR or CT helps.
What lesion can mimic parosteal osteosarc? (two)
cortical desmoid (avulsion injury that is totally benign) or myositis ossificans.
Ewing sarc description...(classic)
permeative, diaphysis long bone, child (classically).
what percentage of Ewing sarc is in diaphysis?
only 40%...remainder being metaphyseal and in flat bones
Other descriptive variations or characteristics of Ewings.
Can be in adolescents and flat bone lesions often in people in their 20's. Most often permeative but can also be sclerotic and have patchy appearance.
What kind of periostitis does Ewings have?
onion skin or sunburst.
classic ddx for a child with a permeative lesion...(3)
Ewings, EG, infection
chondrosarc appearance...
what is difficult to differentiate from chondrosarc?
enchondroma...histology is the same if it is low grade.
what can help differentiate chondrosarc from enchondroma?
pain...only use "possible chondrosarc" if pain is present because it can trigger wide excision.
what radiologic study will help differentiate low grade chondrosarc from enchondroma?
MR...if soft tissue mass or edema is present it is unlikely to be an enchondroma.
any time there is a soft tissue mass with amorphous snowflake calcification in an older patient what dx should be considered?
Most malignant tumors do not need a radiologist to _____
diagnose them...use the biopsy results
what % of Giant Cell tumors are considered malignant...
15%...rarely metastesize to lung. usually considered malignant for their recurrence rate.
how do you tell giant cell malignant tumor from benign
hard...rate of recurrence only...radiographically and histologically identical.