Bone tumors Flashcards
(83 cards)
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”
2
Q
Aggresive appearance characteristics (6)
A
- Indisctinct margins.
- Wide zone of transition.
- Permeative appearance.
- Agressive periosteal reaction.
- Soft tissue component.
- Endosteal scalloping.
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.
4
Q
Agressive “I know what it is” lesions (2)
A
- Osteosarcoma.
- Condrosarcoma.
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.
6
Q
Types of benign periosteal reaction (2)
A
- Normal periosteal anatomy.
- Solid periosteal reaction.
(See examples in the book)
7
Q
Types of malignant periosteal reaction (3)
A
- Lamellamed periosteal reaction.
- Sunburst periosteal reaction.
- Codman triangle.
(See examples in the book)
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”.
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.
10
Q
Pseudopermeative appearance of margins
A
The permeative appearance will extend to the cortex (Seen in osteoporosis and osseous hemangioma).
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).
12
Q
Fallen-fragment sign
A
- The presence of a bone fracture fragment resting dependently in a cystic bone lesion.
13
Q
Aneurysmal or expansile tumor appearance
A
Sugest an aneurysmal bone cyst.
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.
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.
16
Q
Eccentric within bone tumors
A
- Giant-cell tumor.
- Chondroblastoma.
- Aneurysmal bone cyst.
- Non-ossifying fibroma.
- Chondromyxoid fibroma (rare).
17
Q
Central bone tumors
A
- Simple bone cyst.
- Enchondroma.
- Fibrous dysplasia.
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.
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.
20
Q
Osteopoikilosis
A
Autosomal dominant disorder with multiple focuses of enostosis and keloid formation.
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.
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.
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.
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).
25
Osteosarcoma primary types
- More than 10 sub-types (most important ones):
- Conventional (intramedullary).
- Talangiectatic.
- Paraosteal.
- Periosteal.
26
Osteosarcoma generalities
- 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.
27
Conventional osteosarcoma
- 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.
28
Talengiectatic osteosarcoma
- 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.
29
Parosteal osteosarcoma
- 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).
30
Periosteal osteosarcoma
- 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.
31
Synovial chondromatosis
- 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.
32
Enchondroma
- 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.
33
Characteristics of low risk malignant transformation enchondromas (4)
- <4 cm
- Knee or shoulder
- No endosteal scalloping.
- Increase of chondroid mineralization.
34
Characteristics of high risk malignant transformation enchondromas (5)
- Pelvic bone or hip.
- Increase of endosteal scalloping.
- Cortical thinning.
- Increase of size.
- Progressive demineralization.
35
Familial enchondromatosis
- **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
Osteochondroma
- 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
Multiple hereditary exostosis
- 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
Chondroblastoma
- 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
Chondromyxoid fibroma
- 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
Chondrosarcoma
- 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
Non-ossifying fibroma / Fibrous cortical defect
- 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
Fibrous dysplasia
- 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
Fibrous dysplasia related genetic syndromes
- 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
Hemangioma
- 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
Angiosarcoma of bone
- Malignant lesion. Looks and acts agressively.
- Lung metastases are common.
46
Giant cell tumor (osteoclastoma)
- 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
Eosinophilic granuloma (Langerhans histiocytosis)
- 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
Ewing sarcoma
- 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
Multiple myeloma / Plasmocytoma
- 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
POEMS syndrome acronyms
- Polyneuropathy.
- Organomegaly (liver, spleen).
- Endocrine disturbances (amenorrhea, gynecomastia).
- Monoclonal gammopathy.
- Skin changes (Hirsutism and hyperpigmentation).
51
Lymphoma
- 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
Intraosseous lipoma
- 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
Chordoma
- 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
Simple bone cyst
- 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
Aneurysmal bone cyst
- 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
Adamantinoma
- Very rare malignant lytic lesion.
- Occurs in the tibia.
- Soap-bubble appearance.
- Difficult to differenciate from fibrous dysplasia.
57
Osseous metastases generalities
- 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
Lytic osseous metastases (5)
- Lung.
- Breast.
- Thyroid.
- Kidney.
- Stomach, colon.
59
Blastic osseous metastases (5)
- Breast.
- Prostate, seminoma.
- TCC.
- Mucinous tumors.
- Carcinoid
60
Myositis ossificans evolution over time
- 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
Brown tumor
- 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
Myositis ossificans
- 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
Cortical desmoid
- 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
Lipoma
- 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
Well-differenciated liposarcoma/ Atypical lipomatous tumor
- 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
High-grade liposarcoma
- 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
Myxoid liposarcoma
- 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
Fibrolipomatous hamartoma of nerve
- 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
High-grade non-adipocytic sarcoma
- 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
Superficial fibromatosis
- 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
Nodular fasciitis
- 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
Elastofibroma dorsi
- 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
Desmoid fibromatosis
- Benign but agressive neoplasm.
- Abdominal wall most common location.
- Low in signal intensity and enhances variably.
- Associated with Gardner syndrome.
72
Dermatofibroma protuberans
- Slowly growing, intermediate-grade cutaneous malignancy that presents as a superfial skin nodule or mass.
- MR: T2 high-signal, enhances.q
73
Peripheral nerve sheath tumors
- 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
malignant peripheral nerve sheath
- 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
Myxoma
- Benign soft-tissue tumor.
- Myxoid extracellular matrix creates a near fluid-signal intensity appearance, with minimal enhancement.
- Tend to occur in muscles.
76
Synovial sarcoma
- 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
Morton neuroma
- 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
DD of large agressive soft tissue tumor (5)
- Undifferenciated pleomorphic sarcoma.
- Pleomorphic liposarcoma
- Dedifferenciated liposarcoma.
- Rhabdomyosarcoma.
- Leiomyosarcoma
79
DD of T2 hyperintense tumor, circumscribed (4)
- Benign neurogenic tumor.
- Malignant peripheral neurogenic tumor.
- Synovial sarcoma.
- Myxoma.
80
DD of T2 hyperintense tumor, large and agressive (4)
- Synovial sarcoma.
- Malignant peripheral neurogenic tumor.
- Myxoid liposarcoma.
- Myxoidfibrosarcoma.
81
Soft tissue tumor with helpful imaging features (6)
- 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.
