Benign Lytic Lesions

Front 1

FEGNOMASHIC

Back 1

Fibrous dysplasia
Enchondroma and Eosinophilic granuloma
Giant cell tumor
Nonossifying fibroma
Osteoblastoma
Metastatic disease and Myeloma
Aneurysmal bone cyst
Solitary bone cyst
Hyperparathyroidism (Brown tumor)
Infection
Chondroblastoma and Chondromyxoid fibroma

Front 2

Polyostotic fibrous dysplasia, cafe au lait spots, and precocious puberty

Syndrome name?

Back 2

McCune-Albright syndrome

Front 3

Fibrous dysplasia: characteristics

Back 3

Variable appearance
No periosteal reaction
No pain
May be mono or polyostotic
Prefers pelvis, proximal femur, ribs, skul. If in pelvis, always in ispi proximal femur (not vice versa).
Classically ground glass apperance, but may be pure lytic or sclerotic.

Front 4

Adamantinoma

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Malignant tumor that resembles fibrous dysplasia.
Almost always in tibia or jaw.
In DDx of FD in these locations.

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Child with multiple jaw fibrous dysplasia lesions termed:

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cherubism due to puffed out cheeks

jaw lesions regress in adulthood

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Enchondroma: characteristics

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Most common cystic lesion of the phalanges.
Can be in any bone formed from cartilage.
Invariably contain calcified chondroid matrix UNLESS in phalanges.
Difficult to differentiate from chondrosarcoma, pain should prompt surgical investigation.
No periostitis.

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Multiple enchondromas WITHOUT soft tissue hemangiomas

Syndrome?

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Ollier's disease

Not hereditary, NO increased malignant degen of enchondromas

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Multiple enchondromas WITH soft tissue hemangiomas

Syndrome?

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Maffucci's syndrome

Not hereditary, YES increased malignant degen of enchondromas

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Eosinophilic Granuloma: characteristics?

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Highly variable: lytic, blastic, well or ill-defined.
Can be polyostotic.
Can have periostitis.
Can have pain.
HOWEVER, usually age < 30 years, rare in older patients.

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Giant cell tumor, characteristics?

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Cannot tell histologically or radiographically if benign: D&C, pack, and see if recur (15% do).

Four criteria (long bones only):
Only occurs with closed epiphyses.
Always epiphyseal and always abut articular surface.
Eccentrically located (but hard to tell if large).
Sharp, non sclerotic zone of transition (border).

Front 11

Non ossifying fibroma: characteristics?

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Typically metaphysis of long bone arising from cortex.
Typically thin, sclerotic border, scalloped and slightly expansile (75%)
Age < 30.
Asymptomatic
No periositis.

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Difference between non ossifying fibroma and fibrous cortical defect?

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Size:
NOF > 2cm
FCD < 2cm

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Lesions which may have a bony sequestrum?

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EG
osteomyelitis
lymphoma
fibrosarcoma

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Osteoblastoma: characteristics?

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Two appearances: like a large osteoid osteoma or like an ABC.

Rare, but mention when ABC mentioned.

Front 15

DDx of expansile lytic lesion of posterior elements of spine?

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Osteoblastoma
ABC
TB

(OATs)

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Mets or myeloma: characteristics?

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Can appear benign or not. Variable appearances.

Always mention if age >40.

Front 17

Expansile lytic metastatic lesions _tend_ to come from what primaries?

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RCC
Thyroid

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Aneurysmal bone cyst, characteristics:

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Always expansile/aneurysmal
Almost always age < 30

Often painful
May have fluid/fluid levels

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Solitary bone cyst, characteristics:

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Always central
Almost always age < 30

Usually asymptomatic unless fractured.
May demonstrate fallen fragment sign.

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Hyperparathyroidism (brown tumors), characteristics:

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Must have other evidence of hyperparathyroidism (subperiosteal resportion in phalanges, distal clavicles, medial proximal tibias, SI joints)

May appear lytic or sclerotic.

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Osteomyelitis, characteristics:

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Highly variable, in differential of almost all lytic lesions.

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Chondroblastoma, characteristics:

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Always epiphyseal
Always < 30yo

Sometimes calcification.

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DDx of lytic lesion in epiphysis of patient <30yo?

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Infection (most common)
Chondroblastoma
GCT

Consider subchondral cyst if arthritic changes present.

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Chondromyxoid fibroma, characteristics:

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Extremely rate.
Resemble NOF but can be seen at any age.
Mention with NOF.

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Lesions excluded by age >30y?

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EG
chondroblastoma
NOF
ABC
SBC

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Lesions excluded by periostitis or pain (assuming no trauma)?

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fibrous dysplasia
SBC
NOF
enchondroma

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What non-long bones demonstrate epiphyseal lesions?

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tarsal bones, esp calcaneus, carpal bones, patella

apophysis is an epiphyseal equivalent.

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Difference between epiphysis and apophysis?

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Epiphyses contribute to length of bone, apophyses serve as ligamentous attachments.

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What lesions are automatically included in?
Patient <30yo
Patient >40yo

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EG, infection

Mets, infection

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DDx of incidental sclerotic lesion in a 20-40yo?

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NOF
EG
SBC
ABC
chondroblastoma

Front 31

DDx of incidental sclerotic lesion in >50?

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Primarily metastatic disease

Also consider the 20-40yo DDx secondarily.