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99 Cards in this Set

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What are characteristics of synovial sarcoma?
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?
Synovial sarcoma


MFH


Liposarcoma with dystrophic calcification


Surface osteosarcoma
What are umans's 5 end of bone lesions?
Giant cell tumor


Chondroblastoma


Clear cell chondrosarcoma


Lytic phase of Pagets


Intraosseous ganglion
What are the 5 Ds of neuropathic joint?
Density


Debris


Distention


Disorganization


Dissociation
What do these describe?
Hypertrophic variety of neuropathic joint
What are other types of neuropathic joint?
Atrophic


Mixed
What percent is each
Hypertrophic -- only 20%


Atrophic -- 40%


Mixed -- 40%
What is a cause of neuropathic knee?
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?
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?
Post traumatic


Rheumatoid



Hyperparathyroidism
DDx for end of bone lesion in skeletally immature patient?
CHONDROBLASTOMA



osteomyelitis/Brodie abscess



Eosinophilic granuloma
What are the special characteristics of chondroblastoma?
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?
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?
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?
Determine whether process is monostotic or polyostotic
What if it is polyostotic?
Then further work up the additional sites of abnormality with plain film
Then what?
See if you can make a definitive diagnosis by the appearance and distribution of all lesions
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?
Multiple foci of osteomyelitis



All round cell lesions (Langerhans cell histiocytosis,



Neuroblastoma mets



Ewing sarcoma with osseous mets
distal clavicular resorption
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
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
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
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
Hypertrophy due to tendinitis



Xanthofibroma (low signal intensity)



Accessory soleus (MAY BE UNILATERAL)
Diaphyseal to metadiaphyseal lesion with wide zone of transiton in child
Ewings -- always periosteal reaction


Infection



Osteosarcoma -- must have bony matrix



Lymphoma



Egran



Mets from neuroblastoma?
Aggressive fibular head lesion with dense matrix
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
HO


Plain film shows diffuse periosteal reaction
Fragmented patella
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
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
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
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
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
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
Make sure you can see superior surface of T1!!!!!!


SOFT TISSUES
Hand film
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
Baker cyst



(Actually in semimembranosus-gastroc bursa)
Air in Baker cyst?
Infected


Recent history of arthrogram
Large erosion anterior aspect of distal femur
Rheumatoid arthritis


Due to pressure from patellar motion
Suggestive of RA
No productive changes (osteophytes, enthesophytes), no periosteal calcification.

Diffuse JSN

Erosions

Osteopenia
Early RA
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.
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
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
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)
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
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
May be normal.


In order to diagnose osgood schlatters, you need to also have STS and point tenderness
Places where myeloma and plasmacytomas prevalent
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
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
Look at:

Sacrum


SI joints


Iliac horns
pedunculated synovium
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
= Localized gigantism. In this case,

MACRODYSTROPHIA LIPOMATOSA

because second or third digit is involved.
Other causes of localized gigantism
Neurofibromatosis associated bone dysplasia (more generalized when hand involved)


Hypervascularity due to AVM



Lymphangiomatosis associated with Klippel Trenaunay syndrome
Klippel Trenaunay
Soft tissue hemangiomata



Soft tissue and bony limb hypertrophy



AV fistulas
superior articular facets
Concave


Directed posteromedially
Lytic lesion causing endosteal scalloping but not much else in child
Fibrous dysplasia


Eosinophilic granuloma



Solitary bone cyst
Which peaks in age at 5-10
EG
Most common location for EG?
Skull
Next?
Axial skeleton
Next?
Long bones (femur most common)