Msk -- disk
Terms
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- What are characteristics of synovial sarcoma?
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Does not have to be even associated with joint because it does not arise from synovial cells. It was a pathologic misnomer.
Found in young patient popn, typically males.
Frequently calcifies.
Most commonly found in lower extremity - What is the differential diagnosis of a soft tissue mass with calcification?
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Synovial sarcoma
MFH
Liposarcoma with dystrophic calcification
Surface osteosarcoma - What are umans's 5 end of bone lesions?
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Giant cell tumor
Chondroblastoma
Clear cell chondrosarcoma
Lytic phase of Pagets
Intraosseous ganglion - What are the 5 Ds of neuropathic joint?
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Density
Debris
Distention
Disorganization
Dissociation - What do these describe?
- Hypertrophic variety of neuropathic joint
- What are other types of neuropathic joint?
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Atrophic
Mixed - What percent is each
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Hypertrophic -- only 20%
Atrophic -- 40%
Mixed -- 40% - What is a cause of neuropathic knee?
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Not diabetes, since not far distal enough in most cases.
SYPHILIS (tabes dorsalis) - What is always suspicious for mets/myeloma
- Multiple lytic lesions in any patient over age 40
- What is diagnostic of multiple myeloma?
- Multiple punched out lytic skull lesions. More likely than for metsstatic disease, although still in ddx
- What part of spine do mets usually first involve?
- Pedicles
- What about myeloma?
- Vertebral body (makes sense, thats where the marrow is)
- What is ddx for multiple lytic lesions?
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Mets/myeloma
LCH
Hyperparathyroidism (with or without brown tumors) - When you see a large soft tissue mass that is scalloping bone, but not destroying it, what is going on?
- Probably slow growing mass
- What is the DDx for such a lesion?
- Soft tissue desmoid or fibromatosis
- What is a specific variety seen in kids?
- Juvenile aponeurotic fibroma
- What is the location this tumor is most commonly seen?
- Intraosseous membrane of the wrist
- What joints are most commonly affected by RA?
- Hands, wrists, hips, knees. But any joint can become involved.
- DDx for distal clavicular resorption?
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Post traumatic
Rheumatoid
Hyperparathyroidism - DDx for end of bone lesion in skeletally immature patient?
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CHONDROBLASTOMA
osteomyelitis/Brodie abscess
Eosinophilic granuloma - What are the special characteristics of chondroblastoma?
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Eccentrically located within the bone
May be purely lytic or have chondroid matrix
Usually thick sclerotic rim due to inflammatory reaction
Also can see perisoteal reaction a distance from the lesion also due to intense inflammatory reaction. - What are the most common locations for Chondroblastoma?
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1) Proximal humeral epiphysis
2) Proximal femoral epiphysis
3) Distal femoral
4) Proximal tibial - What is the ddx for lytic vertebral body lesion in middle aged patient?
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Mets and Myeloma at top of ddx
Then other malignant lesions such as lymphoma and chordoma (especially if cervical or lower lumbar)
Then benign tumors such as osteoblastoma (more common posterior elements) and giant cell tumor.
Finally, lytic phase of Paget's which can cause bony expansion and some collapse of vertebral body - What is the algorithm for working up an aggressive looking bony lesion?
- First do bone scan
- Then what?
- See if you can make a definitive diagnosis by the appearance and distribution of all lesions
- What if it is polyostotic?
- Then further work up the additional sites of abnormality with plain film
- What if you cannot?
- Go on to biopsy
- What if the process is monostotic?
- Get a chest CT looking for metastatic disease
- What if there is no evidence of thoracic metastatic disease?
- Biopsy the lesion
- What if there is evidence of thoracic metastatic disease?
- Try to determine whether the lesions are related, and if probably are, then maybe biopsy anyway for the oncologists to know what they are dealing with.
- What is an appropriate workup for an aggressive appearing soft tissue lesion?
- YOU CANNOT DETERMINE WHETHER A SOFT TISSUE MASS IS MALIGNANT OR BENIGN JUST BASED ON ITS BORDERS OR ANYTHING LIKE THAT.
- What an appropriate workup then?
- Start with plain film, then do MRI to evaluate what structures it is adjacent to and to characterize it. Then will most likely need to biopsy it, unless it is a truly benign entity (lipoma, gangion cyst, etc)
- DDx for aggressive polyostotic lesions in a child?
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Multiple foci of osteomyelitis
All round cell lesions (Langerhans cell histiocytosis,
Neuroblastoma mets
Ewing sarcoma with osseous mets - distal clavicular resorption
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Unilateral -- Traumatic
Child
Bilateral -- RA
HPT - Comma shaped patella
- When associated with patella alta, indicative of chronic patella alta, probably secondary to flexion contracture. Comma shape is due to remodeling of the inferior patella secondary to chronic compression against superior femoral condyle.
- Anterior tibial lesion
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Besides mets, myeloma and infection:
Fibrous dysplasia
Osteofibrous dysplasia
Adamantinoma
Pagets -- Anywhere else, should contact articular surface, but in anterior tibia, early lytic phase classically occurs in middiaphysis - flattening or fragmentation of femoral epiphysis in child
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AVN
Causes:
1) Older child -- Legg perthes
2) Younger child -- DDH (look for changes of acetabular dysplasia, disloc/sublux of FH, widening of teardrop, etc) - Lateral view of foot
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Achilles pathology
Retrocalcaneal bursitis
Calceneal fracture (LOOK AT BOEHLER'S ANGLE)
Coalition (C or anterior talar beak)
Talar OCD - Lateral view of foot with metatarsals dorsally displaced relative to cuneiforms
- Lisfranc
- Pump bump
- Haglund's
- Rounded lesion in achilles
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Hypertrophy due to tendinitis
Xanthofibroma (low signal intensity)
Accessory soleus (MAY BE UNILATERAL) - Diaphyseal to metadiaphyseal lesion with wide zone of transiton in child
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Ewings -- always periosteal reaction
Infection
Osteosarcoma -- must have bony matrix
Lymphoma
Egran
Mets from neuroblastoma? - Aggressive fibular head lesion with dense matrix
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MFH
Chondrosarcoma
Lymphoma
Fibrosarcoma - Lesion evaluation
- Look at epicenter of lesion to determine space of origin
- Proximal tibiofibular joint
- Synovial, Thus susceptible to PVNS!
- Tram track pattern on bone scan
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HO
Plain film shows diffuse periosteal reaction - Fragmented patella
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Superolateral with multiple fragments that do not fit together nicely = multipartite patella. Fracture does not occur solely in this location. Usually bilateral.
Transverse or burst (peace sign) appearance. Fracture. If more than superolateral patella is involved, think fracture. - Elbow ossification centers
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CRITOE
2,4,6,8,10,12 years
2 years - C - Capitellum
4 years - R - Head of Radius
6 years - I - Internal (Medial) Epicondyle
8 years - T - Trochlea
10 years- O - Olecranon
12 years- L - Lateral (External) Epicondyle - Elbow lines
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Anterior humeral line -- Draw line down anterior aspect of humerus. Should intersect middle 1/3 of capitellar ossification center. If it doesn't, suspect supracondylar fracture, which is usually posteriorly angulated, thus line would cross capitellum too far anteriorly
Radiocapitellar line -- draw line down axis of radius on lateral view. Should pass through center of capitellum. If not, subluxation or dislocation. - Rounded radial head
- Congenital radial dislocation
- Early OA of hip
- Small osteophytes at joint capsule margins
- Unilateral elevation of scapula
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Sprengel's -- congenital non-descent of one scapula
Associated with omovertebral bone -- bony bridge between superomedial scapula and C-spine -- in 1/3 of cases - AVN DDx
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Trauma -- most common
Alcoholism
Steroid use -- can occur up to 3 years after cessation
Sickle cell (or any hemoglobinopathy)
Irradiation
Gauchers
Decompression sickness (Bends or Caisson disease) -- occurs in underwater miners too (need increased pressure to prevent water seepage)
Pancreatitis
Legg-Calve-Perthes, SCFE, and DDH - AVN femoral head stages
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0 -- Abnl MRI, normal bone scan, normal radiographs.
1 -- Abnormal MRI, abnormal bone scan, normal radiographs. Early changes of AVN may be increased signal on T2WI.
2 -- Reparative stage. Begins with demineralization of FH, followed by reparative mottled sclerosis.
3 -- Subcortical lucency (crescent sign) seen just below articular cortex. Represents subchondral fracture/collapse.
4 -- Flattening of FH, normal joint space and acetabulum
5 -- DJD with JSN and involvement of acetabulum as well - Lateral C spine
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Make sure you can see superior surface of T1!!!!!!
SOFT TISSUES - Hand film
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Bony length
Fracture
Soft tissues (also look for gas)
Joint spaces
Erosions
Soft tissue calcification - Hand film with diffusely thickened soft tissues, bony excrescences
- Acromegaly. Should also see cartilage widening and spade-like tufts.
- Thick heel pad
- Acromegaly
- Excessively pneumatized large paranasal sinusus
- Acromegaly
- Fluid mass in semimembranosus muscle
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Baker cyst
(Actually in semimembranosus-gastroc bursa) - Air in Baker cyst?
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Infected
Recent history of arthrogram - Large erosion anterior aspect of distal femur
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Rheumatoid arthritis
Due to pressure from patellar motion - Suggestive of RA
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No productive changes (osteophytes, enthesophytes), no periosteal calcification.
Diffuse JSN
Erosions
Osteopenia - Early RA
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Erosions at intrasynovial extracartilaginous edges of phalanges.
STS
Juxtaarticular osteopenia - Tendon rupture
- Think RA
- RA in the knee
- Valgus
- Large dense soft tissue mass adjacent to bone
- Look for overhanging edges -- GOUT
- Soft tissue mass on MR. Bright on T2 with even brighter tubular channels within the lesion.
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Intramuscular hemangioma.
Replaces, does not displace muscle.
Can have phleboliths on Xray, but not necessary. - Lucent end of bone lesion with narrow zone of transition and nonsclerotic margin
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GIANT CELL TUMOR
Unlikely to be anything else if end of bone, purely lucent, narrow zone of transition, and NON-SCLEROTIC MARGIN - Giant cell tumor
- Purely lytic, ECCENTRIC, near end of bone, narrow zone of transition, no sclerotic margin
- GCT ddx
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These lesions can also have NZT with nonsclerotic margin
Brown tumor (look for other signs of HPT)
Plasmacytoma (should not be so eccentric) - Huge lytic destructive bony mass with THIN CORTICAL RIM (in iliac wing)
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Unlikely to be aggressive lesion such as Ewings
ABC
Hemangiopericytoma
Met (RCCA)
Pseudotumor of Hemophilia (look for associated joint abnormalities) -- represents an intraosseous or periosteal bleed!!! - Dense bones, wormian bones, and acroosteolysis
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Pyknodysostosis
Also small mandibular angle - Dense bones, cutaneous calcifications, basal ganglionic calcifications
- Hypoparathyroidism
- Dense bones, cutaneous calcifications, basal ganglionic calcifications, brachydactyly (short meta carpals and tarsals), and exostoses.
- Pseudohypoparathyroidism
- Same as above without basal ganglionic calcs
- Pseudo pseudo
- What is pseudohypopara?
- end organ resistance to PTH
- What is pseudo pseudo?
- normocalcemic version of pseudohypopara
- Widening of growth plate with loss of prov zone of calc weeks or months after a trauma
- Traumatic osteolysis of growth plate
- bony fragmentation at tibial apophysis
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May be normal.
In order to diagnose osgood schlatters, you need to also have STS and point tenderness - Places where myeloma and plasmacytomas prevalent
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Places where there is still hematopoietic bone marrow
Vertebral bodies
Pelvis
Femur
Humerus - Difference in appearance of plasmacytoma versus myeloma?
- Plasmacytomas are more EXPANSILE lytic lesions
- Expansile lytic metastases
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RCCA
Thyroid - Where can giant cell tumors occur?
- Pubic rami, which must be end of bone equivalents. I think they can occur in apophyses also
- STS adjacent to radial head fracture
- suggests ulnar collateral ligament tear
- Apparently normal AP pelvis
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Look at:
Sacrum
SI joints
Iliac horns - pedunculated synovium
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if some hemosiderin = PVNS
if calc, synov osteochondromatosis - Early RA, where in the hands?
- MCP, carpals, some PIP
- What excludes RA, favoring psoriatic?
- enthesopathy
- Enlargement of second or third digit with gross overgrowth of phalanges and soft tissues
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= Localized gigantism. In this case,
MACRODYSTROPHIA LIPOMATOSA
because second or third digit is involved. - Other causes of localized gigantism
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Neurofibromatosis associated bone dysplasia (more generalized when hand involved)
Hypervascularity due to AVM
Lymphangiomatosis associated with Klippel Trenaunay syndrome - Klippel Trenaunay
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Soft tissue hemangiomata
Soft tissue and bony limb hypertrophy
AV fistulas - superior articular facets
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Concave
Directed posteromedially - Lytic lesion causing endosteal scalloping but not much else in child
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Fibrous dysplasia
Eosinophilic granuloma
Solitary bone cyst - Which peaks in age at 5-10
- EG
- Most common location for EG?
- Skull
- Next?
- Long bones (femur most common)