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Core MSK > Bone tumors > Flashcards

Bone tumors Flashcards

1
Q

Global approach to bone lesions

A
  • Determine if the tumor has agressive or non-agressive appearance, then classify it as “I know what it is” or “I don’t know what it is”
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2
Q

Aggresive appearance characteristics (6)

A
  • Indisctinct margins.
  • Wide zone of transition.
  • Permeative appearance.
  • Agressive periosteal reaction.
  • Soft tissue component.
  • Endosteal scalloping.
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3
Q

Non-Agressive appearance characteristics (6)

A
  • Sclerotic margins.
  • Narrow zone of transition.
  • Well circumscribed.
  • No agressive periosteal reaction.
  • No soft tissue component.
  • No endosteal scalloping.
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4
Q

Agressive “I know what it is” lesions (2)

A
  • Osteosarcoma.
  • Condrosarcoma.
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5
Q

Non-agressive “I know what is is” lesions (7)

A
  • Enchondroma.
  • Osteoid osteoma.
  • Osteochondroma.
  • Non-ossifying fibroma.
  • Hemangioma.
  • Giant cell tumor.
  • Fibrous dysplasia.
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6
Q

Types of benign periosteal reaction (2)

A
  • Normal periosteal anatomy.
  • Solid periosteal reaction.
    (See examples in the book)
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7
Q

Types of malignant periosteal reaction (3)

A
  • Lamellamed periosteal reaction.
  • Sunburst periosteal reaction.
  • Codman triangle.
    (See examples in the book)
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8
Q

Pattern of bone destruction: Margin analysis

A
  • Agressive and non-agressive appearance.
  • A sharply marginated zone of transition denotes as less agressive.
  • A wide zone of transition denotes a more agressive lesion.
  • Can be classified with the “Lodwick classification”.
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9
Q

Lodwick Classification

A
  • Classification of bone destruction, helps to stratify agressiveness:
  • Type 1: Geographic pattern
  • Type 1a: Thin schlerotic margins, almost always non-agressive.
  • Type 1b: Well-defined margins, usually non-agressive
  • Type 1c: Any part of the margin is indistinct.
  • Type 2: Moth-eaten pattern: Difficult to define any border at all. Agressive.
  • Type 3: Permeative: Multiple tiny holes that infiltrate bone. Very agressive. Seen in Lymphoma, leukemia, and Ewing sarchoma.
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10
Q

Pseudopermeative appearance of margins

A

The permeative appearance will extend to the cortex (Seen in osteoporosis and osseous hemangioma).

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11
Q

Types of matrix production

A
  • Osteoid lesions: Fluffly cloud-like bone. (Ex. malignant osteosarcoma).
  • Chondroid lesions: Ring and arc or pop-corn like appearance (Ex. benign enchondroma or malignant chondrosarcoma).
  • Ground glass matrix: Blurring of trabeculae (Ex: Fibrous dysplasia).
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12
Q

Fallen-fragment sign

A
  • The presence of a bone fracture fragment resting dependently in a cystic bone lesion.
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13
Q

Aneurysmal or expansile tumor appearance

A

Sugest an aneurysmal bone cyst.

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14
Q

Hyperparathiroidism manifestations in the bones

A
  • Subchondral reabsortion (Distal clavicles, symphisis pubis, SI joint).
  • Tumoral calcinosis.
  • Brown tumors.
  • Acro-osteolysis.
  • Rugger jersey spine.
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15
Q

Patient age in agresive bone lesions

A
  • Agressive lytic bone lesion >40 years old: Metastasis or myeloma.
  • Agressive lytic bone lesion <20 years old: Eosinophilic granuloma, infection or Ewing sarcoma.
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16
Q

Eccentric within bone tumors

A
  • Giant-cell tumor.
  • Chondroblastoma.
  • Aneurysmal bone cyst.
  • Non-ossifying fibroma.
  • Chondromyxoid fibroma (rare).
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17
Q

Central bone tumors

A
  • Simple bone cyst.
  • Enchondroma.
  • Fibrous dysplasia.
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18
Q

Enostosis (bone island)

A
  • Benign.
  • Small spiculated osteoblastic focus.
  • It may be rarely difficult to differenciate from osteoblastic metastasis, osteoid osteoma or low-grade osteosarcoma.
  • Giant variant >2 cm may be most difficut to differenciate from low-grade osteosarcoma.
  • Bone scan is normal.
  • Associated with mixed schlerosis bone dysplasia: Osteopoikilosis, melorheostosis and osteopathia striata.
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19
Q

Osteopathia striata

A
  • Voorhoeve disease
  • Benign, asymptomatic sclerotic dysplasia characterized by linear bands of sclerosis in the long bones and fan-like sclerosis in the flat pelvic bones.
  • Bone scan is normal.
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20
Q

Osteopoikilosis

A

Autosomal dominant disorder with multiple focuses of enostosis and keloid formation.

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21
Q

Osteoma

A
  • Slow growing lesions that may arise from the cortex of the skull or the frontal/etmoidal sinuses.
  • Gardner syndrome: Multiple osteomas, intestinal polyposis and desmoid tumors.
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22
Q

Melorheostosis

A
  • Pain, decreased range of motion, leg bowing and leg-length discrepancy.
  • Associated with schleroderma-like skin lesions.
  • Distribution of a single dermathome.
  • Non-neoplasic proliferation of thickened and irregular cortex with typical candle-wax appearance.
  • Intense uptake on bone scan.
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23
Q

Osteoid osteoma

A
  • Benign osteoblastic lesion.
  • Typically in children.
  • Lucent nidus of osteoid tissue (may be with central calcification) surrounded by reactive bone sclerosis.
  • Presentation: Nocturnal pain relieved by aspirin in a teenager or young adult.
  • Tends to occur in diaphyses of leg long bones.
  • 20% in posterior vertebral elements.
  • Double density sign at bone scan (hotter spot within hot area sign).
  • MRI: nidus is T1 low-signal and reactive marrow edema can obscure de lesion on T2.
  • Treatment: Radiofrequency ablation, surgical curettage or resection.
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24
Q

Osteoblastoma

A
  • Benign osteoid-producing tumor.
  • Histologically is the same as a osteoid osteoma, only that it is >2 cm in size.
  • 4 times less common that osteoid osteoma.
  • Presentation: Nocturnal pain not relieved by aspirin in a teenager or young adult.
  • Most commonly in posterior elements of the spine, also in diaphyses of leg long bones.
  • Lytic apprearance with mineralization, may have a secondary aneurysmal bone cyst.
  • Lytic lesion in the posterior elements of the spine in a young person may be osteoblastoma or aneurysmal bone cyst (The last does not have mineralization).
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25
Q

Osteosarcoma primary types

A
  • More than 10 sub-types (most important ones):
  • Conventional (intramedullary).
  • Talangiectatic.
  • Paraosteal.
  • Periosteal.
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26
Q

Osteosarcoma generalities

A
  • Heterogeneous group of malignant tumors.
  • Cells derived from osteoid linage, most of them produce an osteoid matrix.
  • Primary: 10 sub-types.
  • The most common primary type is the conventional.
  • Secondary: Paget disease or radiation.
  • Hallmarks: Bony destruction, production of osteoid matrix, agressive periosteal reaction and soft-tissue mass.
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27
Q

Conventional osteosarcoma

A
  • 75% of osteosarcomas.
  • Occurs in adolescent/young adults usually at the knee in the metaphysis of the femur or tibia.
  • Features: Intramedullary osteoid matrix, intramedullary and cortical bone destruction, agressive periosteal reaction (sunburst or codman) and soft-tissue mass.
  • MRI: T1 low-signal, T2 high-signal (edema) and T2 low-signal (sclerosis) areas.
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28
Q

Talengiectatic osteosarcoma

A
  • Osteolytic destructive sarcoma.
  • May mimic a benign aneurysmal bone cyst.
  • Vascular, with large cystic spaces filled with blood.
  • Does not produce any osteoid matrix components.
  • The presence of nodular components at MRI differenciates it from a benign aneurysmal bone cyst.
  • MRI: Heterogeneous lesion with T2 high-signal and areas of enhancement at T1-post contrast.
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29
Q

Parosteal osteosarcoma

A
  • Juxtacortical osteosarcoma that arises from the outer periosteum.
  • Most commonly occurs at the posterior aspect of the distal femoral metaphysis.
  • Cauliflower-like exophytic morphology.
  • Least malignant of all osteosarcomas (90% five-year survival).
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30
Q

Periosteal osteosarcoma

A
  • Juxtacortical osteosarcoma that arises from the inner periosteum.
  • <20 years old, commonly at the diaphysis of the femur or tibia.
  • Cortical thickening, agressive periosteal reaction and soft-tissue mass.
  • Histologically may show chondroid differentiation.
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31
Q

Synovial chondromatosis

A
  • Synovial metaplasia with formation of intra-articular lobulated cartilaginous nodules.
  • When ossified it is called osteochondromatosis.
  • May produce mechanical erosions and secondary OA.
  • Most common location is the knee. Other locations: Shoulders, hip and elbows.
  • Radiography shows multiple round intra-articular bodies of similar size and variable mineralization.
  • MRI appearance is variable: Multiple globular and rounded foci of low signal - DD in MRI: pigmented villonodular synovitis, which do not calcify.
  • Very rarely: malignant degeneration to chondrosarcoma.
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32
Q

Enchondroma

A
  • Benign lesion of mature hyaline cartilage rests.
  • In the long bones it features the classic popcorn and ring and arc calcifications
  • DD: Bone infarct (serpentine sclerosis) and chondrosarcoma.
  • MRI: Lobulated T2 high-signal.
  • At the hand typically doesn’t produce chondroid matrix and appears as a geographic lytic lesion.
  • May be complicated with pathological fracture at the hand.
  • Very rarely: malignant degeneration to chondrosarcoma, except in multiple enchondromas of Ollier and Maffucci syndromes.
  • Worrisome clinical findings: New pain in abscence of fracture.
  • No universal law for following, depends if it has high or low risk of malignant transformation.
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33
Q

Characteristics of low risk malignant transformation enchondromas (4)

A
  • <4 cm
  • Knee or shoulder
  • No endosteal scalloping.
  • Increase of chondroid mineralization.
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34
Q

Characteristics of high risk malignant transformation enchondromas (5)

A
  • Pelvic bone or hip.
  • Increase of endosteal scalloping.
  • Cortical thinning.
  • Increase of size.
  • Progressive demineralization.
35
Q

Familial enchondromatosis

A
  • Ollier syndrome: Non-hereditary, sporadic, multiple enchondromas principally located in the metaphyseal regions.
  • Maffucci syndrome: Congenital nonhereditary mesodermal dysplasia, multiple enchondromas with venous malformations producing phleboliths.
  • Increased risk of malignant transformation, specially the Maffucci syndrome.
36
Q

Osteochondroma

A
  • Benign carthilage-capped bony growth projecting outward from the bone.
  • The most common benign bone lesion.
  • Clinically pablable mass.
  • Key features: Continuity of cortex of host bone and communication with the medullary cavities.
  • Arises from the metaphysis and grows away from the epiphysis.
  • Uncommon complication: Malignant transformation to chondrosarcoma.
  • Suspect transformation: Pain without fracture, associated soft-tissue mass and a cartilage tap thickness >2 cm on MRI.
  • Multiple osteochondromas can be seen in Multiple hereditary exostosis.
37
Q

Multiple hereditary exostosis

A
  • Autosomal dominant skeletal dysplasia.
  • Incomplete penetrance in females.
  • Most patients are diagnosed by the age of 5 years.
  • Multiple osteochondromas.
  • Knees most commonly involved.
  • Increased risk of malignant transformation.
38
Q

Chondroblastoma

A
  • Benign lesion.
  • Located eccentrically in the epiphysis of a long bone in
    a skeletally immature patient.
  • Most commonly knee or proximal humerus.
  • Calcified chondroid matrix visible in almost all CT studies, but only visible in 50% of RX.
  • MRI: T2 low or intermediate signal.
  • Treatment: Curettage, cryosurgery, or radiofrequency ablation.
  • Rarely malignant.
39
Q

Chondromyxoid fibroma

A
  • Very rare benign cartilage tumor.
  • Eccentric in the tibial or femoral metaphysis about the knee.
  • Rarely demonstrates chondroid matrix.
  • Usually has schlerotic margins on RX.
  • MRI: T2 high-signal.
40
Q

Chondrosarcoma

A
  • Malignant tumor of cartilage.
  • Multiple primary and secondary variants.
  • Secondary: Enchondroma (more commonly from Maffucci and Ollier syndromes), paget disease and osteochondroma.
  • The conventional (intramedullary) is the most common.
  • Findings: Expensile lesion in the medullary bone, with ring and arc chondroid matrix, thickening of the cortex, endosteal scalloping and soft tissue mass.
  • Other types: dedifferenciated, mesenchymal and clear cell.
41
Q

Non-ossifying fibroma / Fibrous cortical defect

A
  • Asymptomatic common incidental radiolucent lesion in the long bones in children and adolescents.
  • They are the same disease. non-ossifying fibroma is reserved only when > 2 cm or symptomatic.
  • Arises from periosteum.
  • Imaging: Multiloculated, lucent lesion with a narrow zone of transition, schlerotic margin and no matrix calcifications.
  • CT, MRI: Cortical disruption or thinning, representing the replacement of the cortex with fibrous tissue.
  • Most undergo spontaneous sclerotic involution in adulthood.
42
Q

Fibrous dysplasia

A
  • Benign congenital non-neoplasic condition.
  • Affects children and young adults.
  • Replacement of normal cancellous bone by abnormal fibrous tissue.
  • Can affect one bone (monostotic) or multiple bones (polyostotic).
  • Common complication: pathological fracture, specially at the femoral neck.
  • In long bones tend to be central and metadiaphyseal, causing bowing deformity (Ex: extreme varus of the sheperd’s crook).
  • Ribs and long bones: Matrix is typically indistinct and ground glass.
  • Pelvic bones: Cystic
  • Skull base: Expansile (DD paget disease).
  • Related to some genetic syndromes.
43
Q

Fibrous dysplasia related genetic syndromes

A
  • McCune-Albright syndrome: Polyostotic fibrous dysplasia, precocious puberty and cutaneous cafe au lait spots.
  • Mazabraud syndrome: Fibrous dysplasia and intramuscular myxomas, which tend to occur in the same region of the body.
44
Q

Hemangioma

A
  • Benign lesion.
  • Typically occurs in the vertebral body, characterized by vascular channels lined with endothelial cells.
  • May be associated with a soft-tissue mass that can cause neurologic compromise.
  • Causes reactive trabecular thickening in response to bony resorption by vascular channels.
  • RX and CT: Corduroy striations and polka dot sign
  • MRI: T1 and T2 high-signal.
45
Q

Angiosarcoma of bone

A
  • Malignant lesion. Looks and acts agressively.
  • Lung metastases are common.
46
Q

Giant cell tumor (osteoclastoma)

A
  • Epiphyseal lucent lesion located eccentrically at the articular end of long bones in skelletally mature patients.
  • Age 20-40 years old.
  • Multinucleated giant cell, similar to an osteoclast.
  • 5% are malignant.
  • Usually seen in paget disease or hyperparathyroidism.
  • Treatment: Curattage or wide resection.
47
Q

Eosinophilic granuloma (Langerhans histiocytosis)

A
  • Caused by abnormal proliferation of histiocytes.
  • Seen in children 5-10 years old.
  • Skull: Geographic skull and lytic lesions with a beveled edge (hole in a hole).
  • Mandible or maxillar: Floating tooth from resorption of alveolar bone.
  • Spine: Vertebra plana (Most common cause in children).
  • Long bones: Destructive lucent lesion with agressive (often lamellated) periosteal reaction, similar to lymphoma/leukemia or Ewing sarcoma.
48
Q

Ewing sarcoma

A
  • Highly malignant small round cell tumor.
  • Affects children and adolescents.
  • Male predominance.
  • Second most common pediatric primary bone tumor.
  • Presentantion: Non-specific, pain, systemic symptoms and fever.
  • RX: Agressive lesion, permeative bone destruction, agressive periosteal reaction, soft-tissue mass.
  • DD: Osteomyelitis, eosinophilic granuloma, lymphoma/leukemia, metastatic neuroblastoma.
49
Q

Multiple myeloma / Plasmocytoma

A
  • Most common primary malignant bone tumor in >40 year olds.
  • Most common presentation: Multiple lytic lesions, with the most severe form being diffuse myelomatosis with endosteal scalloping.
  • Sclerosing myelomatosis in an uncommon variant related to POEMS syndrome.
  • DD: Lytic metastases.
  • Solitary tumor: Plasmocytoma.
50
Q

POEMS syndrome acronyms

A
  • Polyneuropathy.
  • Organomegaly (liver, spleen).
  • Endocrine disturbances (amenorrhea, gynecomastia).
  • Monoclonal gammopathy.
  • Skin changes (Hirsutism and hyperpigmentation).
51
Q

Lymphoma

A
  • Primary bone lymphoma is very rare, tends to occurr in adults over 40.
  • Presentation: Agressive lytic lesion, also an important DD for an ivory (diffusely sclerotic) vertebral body.
  • Often associated with an adjacent soft-tissue mass.
52
Q

Intraosseous lipoma

A
  • Uncommon benign neoplasm.
  • Common sites: Calcaneus, subtrochanteric region of the femur, distal tibia/fibula and metatarsals.
  • Appearance: non-specific circumscribed lucent lesion, thin rim of peripheral sclerosis, may have a central or ring-like calcification.
  • DD: Simple bone cyst, aneurysmal bone cyst.
53
Q

Chordoma

A
  • Malignant lesion derived from a notochord remnant.
  • It arises in the midline of the axial skeleton, either in the spheno-occipital region, body or C2 or sacrococcygeal location.
  • Destructive lytic lesion with irregular scalloped borders.
  • Calcifications may be present from necrosis.
  • MRI: Lobulated T2 high-signal and heterogeneous enhancement.
54
Q

Simple bone cyst

A
  • Benign local disturbance of bone growth in children and adolescents.
  • It is either hollow or fluid-filled.
  • Found in the proximal diaphysis of the humerus or femur.
  • Lacks periosteal reaction (if there is no fracture).
  • 66% complicated with pathological fracture (fallen fragment sign).
  • Always located centrally within a bone.
  • Non-surgical treatment option: injection of methylprednisolone, which induces osteogenesis.
55
Q

Aneurysmal bone cyst

A
  • Expansile or aneurysmal multicystic lesion seen in children and adolescents.
  • Blood-filled sinusoids and solid fibrous elements.
  • Can be central or eccentric, at the posterior elements of the spine.
  • Often presents a smooth periosteal reaction at the proximal and distal aspects.
  • Fluid levels are present.
56
Q

Adamantinoma

A
  • Very rare malignant lytic lesion.
  • Occurs in the tibia.
  • Soap-bubble appearance.
  • Difficult to differenciate from fibrous dysplasia.
57
Q

Osseous metastases generalities

A
  • 10 times more common than primary bone tumors.
  • Most occur in the red marrow, mostly in the axial skeleton.
  • Involvement from the vertebral pedicle or posterior vertebral body suggests MX.
  • Fracture of the lesser trochanter should raise concern for pathologic fracture.
  • Single sternal lesion in a patient with breast cancer is highly predictive for metastases.
58
Q

Lytic osseous metastases (5)

A
  • Lung.
  • Breast.
  • Thyroid.
  • Kidney.
  • Stomach, colon.
59
Q

Blastic osseous metastases (5)

A
  • Breast.
  • Prostate, seminoma.
  • TCC.
  • Mucinous tumors.
  • Carcinoid
60
Q

Myositis ossificans evolution over time

A
  • 1-2 weeks: Soft-tissue mass only.
  • 3-4 weeks: Amorphous osteoid matrix.
  • 5-8 weeks: Periphery evolves to compact bone.
  • 6 months: Ossification continues.
  • > 6 months: Decreases in size.
60
Q

Brown tumor

A
  • Benign lytic lesion seen in patients with hyperparathyroidism.
  • Increased osteoclast activation.
  • Difficult to differenciate from a giant cell tumor.
  • Associated features of HPT: osteopenia, subperiosteal bone resorption and soft-tissue calcifications.
  • Lab: increase in PTH, Ca and P.
  • If HPT is secondary to renal failure, secondary findings of renal osteodystrophy may be seen
  • Non-specific lytic lesion with faint sclerotic margins.
  • Renal osteodystrophy and secondary hyperparathyroidism: Rugged jersey spine, alternating bands of sclerosis and relative central lucency of vertebral body.
60
Q

Myositis ossificans

A
  • Heterotopic bone formation in the skeletal muscle secondary to injury.
  • Most commonly at the eblow or thigh.
  • If suspected do not make biopsy (histology may resemble sarcoma).
  • May mimic paraosteal sarcoma (usually more calcified centrally).
  • Appearance evolves over time.
61
Q

Cortical desmoid

A
  • Also called “Bufkin lesion”
  • Distal femoral cortical defect.
  • Classic “do not touch lesion”.
  • Due to repetitive stress at the attachment of the medial head of gastrocnemius or distal adductor magnus.
  • RX: Saucer-shaped lucent cortical irregularity with sclerotic margins at the posteromedial aspect of the distal femoral metaphysis.
  • MRI: T1 low-signal, T2 high-signal enhancing cortical based lesion.
62
Q

Lipoma

A
  • Benign proliferation of adipocytes.
  • The most common soft-tissue tumor.
  • Not all palpable masses are lipomas.
  • A minimal amount of lesions may have non-adipose tissue.
  • Wispy septations are common.
  • Not resected or biopsed unless there are atypical findings or symptoms.
  • MRI: lobulated T1 high-signal, saturates with T1 FATSAT, slight increase of signal in STIR.
63
Q

Well-differenciated liposarcoma/ Atypical lipomatous tumor

A
  • Low-grade adipocytic neoplasm that rarely metastasizes but can be locally agressive.
  • Larger size, thickened septae, septal or nodular contrast enhancement or increased signal intensity on fluid sensitive sequences.
64
Q

High-grade liposarcoma

A
  • Both pleomorphic liposarcoma and dedifferentiated liposarcoma.
  • Large mass with heterogeneous enhacement and central necrosis.
  • Fatty elements may or may not be present.
  • Similar to: undifferentiated pleomorphic sarcoma, rhabdomyosarcoma or leiomyosarcoma.
65
Q

Myxoid liposarcoma

A
  • High-grade neoplasm different from other adipocytic neoplasms.
  • It’s myxoid component creates a homogeneous T2 high-signal.
  • Fatty elements may not be apparent.
66
Q

Fibrolipomatous hamartoma of nerve

A
  • Rare benign neoplasm of peripheral nerves.
  • Fibroadipose tissue proliferates and infiltrates the epinerium and perinerium.
  • Common location: median nerve of the wrist.
  • Associated with macrodystrophia lipomatosa: Rare congenital localized gigantism.
67
Q

High-grade non-adipocytic sarcoma

A
  • These neoplasms are not realiably distinguisable from each other on imaging.
  • High-grade tumors that frequently metastasize, usually large at presentation.
  • Undifferentiated pleomorphic sarcoma: Mass with heterogeneous enhancement, central necrosis.
  • Rhabdomyosarcoma: High-grade tumor from skeletal muscle origin.
  • Leiomyosarcoma: High-grade tumor from smooth muscle origin.
  • Myxofibrosarcoma: High-grade tumor with myxoid and fibrous elements. Characteristic hyperintense appearance on T2-weighted images.
68
Q

Superficial fibromatosis

A
  • MRI: Nodular foci of various signal intensity.
  • Palmar (Dupuytren contracture): Painless subcutaneous nodules of the palmar surface of the hand, treatment is QX.
  • Plantar fibromatosis (Ledderhose disease): Younger patients, treatment is conservative.
69
Q

Nodular fasciitis

A
  • Benign but rapidly growing non-neoplasic lesion.
  • May mimic sarcoma clinically and on imaging.
  • Masses can be subcutaneous or deep in location.
  • MRI: T2 high-signal. Enhances.
  • Usually ends at biopsy.
70
Q

Elastofibroma dorsi

A
  • Rare, benign mass.
  • Arises in the subescapular region, more commonly at the right.
  • Typically middle-aged females.
  • Reactive pseudotumor due to mechanical irrigation.
  • Images: Alternating bands of fibrous and fatty tissue in a crescentic-shaped mass located deep to latissimus dorsi in the infraescapular region.
71
Q

Desmoid fibromatosis

A
  • Benign but agressive neoplasm.
  • Abdominal wall most common location.
  • Low in signal intensity and enhances variably.
  • Associated with Gardner syndrome.
72
Q

Dermatofibroma protuberans

A
  • Slowly growing, intermediate-grade cutaneous malignancy that presents as a superfial skin nodule or mass.
  • MR: T2 high-signal, enhances.q
73
Q

Peripheral nerve sheath tumors

A
  • Schwannoma and neurofibroma.
  • 10% of benign soft tissue tumors.
  • Typically they look the same, but schwannoma may be eccentric to the nerve and neurofibroma more fusiform mass-like expansion of the nerve.
  • MRI: T2 high-signal, avidly enhances.
  • Split fat pad sign: Peripheral triangle of preserved fat at the proximal and distal margins of the mass.
  • Target sign: Central region of low signal intensity of T2.
  • May be similar to malignant peripheral nerve sheath tumors.
74
Q

malignant peripheral nerve sheath

A
  • Highly associated with neurofibromatosis type I (50% of cases).
  • Cannot be differenciated from benign types on imaging.
  • Signs of malignancy: Larger size, ill-defined margins, central necrosis and rapid growth.
  • PET-CT is an excellent modality to determine the need of biopsy.
75
Q

Myxoma

A
  • Benign soft-tissue tumor.
  • Myxoid extracellular matrix creates a near fluid-signal intensity appearance, with minimal enhancement.
  • Tend to occur in muscles.
76
Q

Synovial sarcoma

A
  • High-grade mesenchymal tumor.
  • Adolescents and young adults.
  • MRI: Homogeneously T2 high-signal, isointense to fluid.
  • Does not communicate with a joint.
  • Contrast should be administered.
  • Internal complexity should be conspicuous.
77
Q

Morton neuroma

A
  • Non-neoplasic benign masses.
  • Occur due to degeneration and fibrosis around a plantar digital nerve of the foot.
  • Most commonly occurs at the level of the metatarsal heads in the second and third interspaces.
  • Clinically: burning pain, more common in females.
  • MRI: Dumbell or teardrop shaped, T2 low-signal with variable enhancement.
  • US: Hypoechoic mass in the intermetatarsal space.
  • Associated with intermetatarsal bursitis.
  • Treatment is conservative.
78
Q

DD of large agressive soft tissue tumor (5)

A
  • Undifferenciated pleomorphic sarcoma.
  • Pleomorphic liposarcoma
  • Dedifferenciated liposarcoma.
  • Rhabdomyosarcoma.
  • Leiomyosarcoma
79
Q

DD of T2 hyperintense tumor, circumscribed (4)

A
  • Benign neurogenic tumor.
  • Malignant peripheral neurogenic tumor.
  • Synovial sarcoma.
  • Myxoma.
80
Q

DD of T2 hyperintense tumor, large and agressive (4)

A
  • Synovial sarcoma.
  • Malignant peripheral neurogenic tumor.
  • Myxoid liposarcoma.
  • Myxoidfibrosarcoma.
81
Q

Soft tissue tumor with helpful imaging features (6)

A
  • Fibrolipomatous hemartoma: Cord-like appearance).
  • Neurogenic tumor: Split fat sign, target sign, arising from a known nerve).
  • Lipoma: Nearly entirely fat signal.
  • Atypical lipomatous tumor: Predominantly lipomatous signal, with some degree of complexity.
  • Morton neuroma: Dumbbell-shapped/teardrop mass at the head of the metatarsals, usually enhancing, typical eccentric at the plantar aspect.
  • Elastofibroma dorsi: Striations of alternating fat and soft tissue, located subscapular deep to latissimus dorsi.

Core MSK (6 decks)

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