Diapositive 1

IMAGING OF

Introduction  Synovial Sarcoma (SS) is a mesenchymal malignant tumor  It represent 5 to 10% of soft tissues tumors  Two features associated with synovial sarcoma that may lead to

an initial mistaken diagnosis of a benign indolent process are slow growth (average time to diagnosis, 2–4 years) and small size

 Imaging has an important role in the assessment of this tumor

although appearance is not specific  We present 11 observations of soft tissue Synovial Sarcoma of

limbs, emphasising their imaging characteristics with review of the literature

Patients and Methods 

Since 1995, 11 observations of soft tissue Synovial Sarcoma of limbs have been detected.

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All patients had radiographs, 2 were examined by high resolution ultrasound, 4 by CT and 9 by MRI.

Results 

6 women and 5 men were included in the study

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The were aged between 13 to 64 years with a mean of 36 years

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Location : 

The lower limbs were involved in 9 cases: knee (n=5) , 1 in thigh (n= 1) leg (n= 1), ankle (n= 1) and foot (n= 1)

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2 tumors were located in the upper limb: forearm (n= 1), shoulder (n= 1).

Results 

9 Synovial Sarcoma had a juxta-articular location.

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2 were located in soft tissues of leg and in that of thigh, away from the joint.

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The size of the tumors ranged from 4 to 14 cm with an average

of 7.8 cm.

Results : Radiographs Radiographs showed a soft tissue mass, associated with calcifications in 3 cases, osteolysis in 2 cases, unilamellar periosteal reaction in one case, and bone condensation facing the mass in one case

Fig. 1

Fig. 2

Radiographs Fig.1 and 2: Juxta-articular calcified soft tissue mass. Fig. 3

Fig. 3: Juxta-articular soft tissue mass with osteolysis and periosteal new bone formation of radius.

Results : Ultrasound Ultrasound showed echoic and heterogenous appearance, sometimes with calcifications with increased Doppler Fig. 5 signal.

Fig. 4

Fig. 4 and Fig. 5: Ultrasound of the knee heterogenous solid mass of the infrapatellar knee region with increased Doppler Signal.

Results : CT Scan CT confirmed showed a solid soft tissue mass in three cases and a multiloculated cystic mass in one case. Calcifications within lesions were observed in two patients and a bone lesion in 3 patients. Fig. 6

Fig. 6 (Same case as Fig and 5) transversal CT view of the knee in soft tissue algorithm:

solid infrapatellar soft tissue mass containing coarse calcifications, and infiltrating the subcutaneous tissue.

Results : MRI 

On MRI, the tumor had well defined margins in all cases

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In 8 patients, MRI signal intensity was intermediate to low compared to muscle on T1, high on T2, with heterogenous enhancement after IV Gadolinium injection

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In 4 patients, the signal was high and heterogenous on T2 with a "triple signal" appearance

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In one case, there was a multiloculated cystic appearance: Low intensity signal on T1, high intensity signal on T2 with internal septa enhancement after injection

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In 4 patients an associated bone lesion was revealed by MRI

Fig. 7

Fig. 8

Axial T1-weighted image

Sagittal T2-weighted image

Fig. 7 and Fig. 8: Well defined mass with a low signal on T1 weighted images and a heterogenous high signal on T2 weighted images.

Fig. 11

Fig. 9

Fig. 10

Fig. 11: Axial T2-weighted image Fig. 9 and Fig. 10: Sagittal T1-weighted image before and after IV Gadolinium injection Soft tissue mass having an intermediate signal (similar to muscle) on T1 (Fig. 9), heterogenous high signal on T2 (Fig. 11) and a heterogenous enhancement after IV Gadolinium injection (Fig. 10)

Fig. 12

Fig. 12: Sagittal T2-weighted image, "Triple signal" appearance

Fig. 13

Fig. 13: Sagittal T1-weighted image

Fig. 14

Fig. 14: Sagittal T2-weighted image

Synovial Sarcoma of the knee with Cystic appearance on MRI : low T1 (Fig. 13) and high T2 signal (Fig. 14)

Discussion : Epidemiology  4th most frequent soft tissue neoplasms representing 2.5 to

10% [1,2]  Occurs mainly in young adults : 15 – 40 years old  80%–95% of synovial sarcomas occur in the limbs.  60%–71% lower limb  16%–25% upper limb [1,4,5,6,7]  Despite its name, less than 10% of SS arise within a joint  Mostly adjacent (40%–50% ) or nearby (60%–75%)a joint

space, with a mean diatance of 5 cm.  Intra-articular involvement is more commonly due to the extension of a juxta-articular neoplasm [1-2-3].

Discussion : Pathology  Synovial sarcoma is an intermediate to high grade tumor.  There are three main histologic subtypes of synovial sarcoma:

biphasic (20%-30%), monophasic(50-60%), and poorly differentiated (15-25%) [1,8].  Grading of synovial sarcoma is achieved by applying the grading

scheme for all sarcomas by the FNCLCC (French Federation Nationale des Centres de Lutte Contre le Cancer) : degree of differentiation, mitotic activity, and necrosis.  The cytogenetic aberration of the t(X;18) translocation is highly

specific for synovial sarcoma [1,23]. :  Observed in 90% of synovial sarcoma  Not found in other tumors

Discussion : Radiographs  Radiographs are normal in 50% of cases  Otherwise they typically show nonspecific, round to oval

juxta-articular soft-tissue masses  Calcifications are identified in up to 30% of synovial

sarcomas. These are often eccentric or peripheral within and nonspecific in appearance [1,9]  Extrinsic bone erosions or periosteal new bone formation

have been reported in 11%–20% of cases  Aggressive bone invasion is far less common (5% of cases)

Discussion : Ultrasound The US appearance of synovial sarcoma:  In 66% of cases: focal, nodular, round or lobulated, solid

hypoechoic soft-tissue mass

 In 14%: prominent heterogeneity with irregular margins  20% of cases: complex sonographic appearance  Doppler US demonstrates vascularity in the areas of viable

tumor (1,11)

Discussion : CT  Is not a good imaging modality for the assessment of soft tissue

tumors.  Non specific appearance : heterogenous multinodular soft-tissue mass  Areas of lower attenuation representing necrosis or hemorrhage are

also common (1,9,11)  Interesting to show calcifications

( 27%–41%) and adjacent bone

abnormalities ( nearly 25% of lesions)  A cystic form had been described in a minority of cases (12,24)

Discussion : MRI  Is the method of choice in the assessment of soft tissue tumors  On T1-weighted MR images: heterogeneous multilobulated soft tissue

mass with intermediate to low signal 

On T2-weighted MR images:

heterogeneity with predominant high

signal intensity (1,22), sometimes a multilobulated mass with intervening septa.  The enhancement is more commonly heterogeneous (83%–100%) than

homogeneous (0%– 17%).  It may be diffuse, Peripheral, nodular , with or without thick septa in

largely necrotic lesions

Discussion : MRI  Areas of haemorrhage, are seen as fluid levels or foci of high signal

intensity on T1- and T2-weighted MR images (47%)  The triple sign: Described by Jones et al (see Fig 12)

- Is the result of intermixed areas of low (calcified or fibrotic collagenized regions), intermediate (solid cellular elements), and high signal intensity on T2 (hemorrhage or necrosis) - It has been described as occurring in 35%–57% of cases but also seen in other soft-tissue neoplasms (1,21,22)  Bone involvement, manifested either by cortical erosion or invasion of

the marrow space (21% )

 Frequently invade adjacent muscle

Discussion : MRI  Diffusion shows an increased signal in benign soft tissue masses

compared to their malignant counterparts, whereas the ADC

values between these groups are not significantly different. This difference can be explained by the contribution of perfusion to the ADC values [26].

 The dynamic contrast-enhanced MR imaging appearance of

synovial sarcoma may be a rapid progressive linear increase in signal intensity followed by washout or plateau (60%), or a late

sustained increase in enhancement after the initial rapid enhancement (40%) [1]

Discussion : PET and SCINTIGRAPHY  Scintigraphic evaluation reveal prominent increased

uptake. It has an important role in the detection of possible metastatic disease and in monitoring response to therapy [1,25]  Positron emission tomography demonstrates marked

increased tracer accumulation [1,10]

Discussion : Criteria for imaging grading Statistically significant imaging features that favored a high Grade synovial sarcoma  Absence of calcification  Presence of cystic components  Presence of hemorrhage  Presence of the triple sign

Imaging findings that were seen only with high-grade lesions :  Cystic components  Hemorrhage  Fluid levels  The triple sign [1]

Discussion : Treatment  The current treatment of choice is wide local excision :  The surgical margins should be closely evaluated to

determine the need for adjuvant therapy  Amputation should be reserved for those cases in which gross resection of the tumour and preservation of a functional limb is not possible [1]

 Radiation therapy plays an important role in the treatment of

marginally resected tumours  Initiated preoperatively if the surgeon believes that the surgical margins will be positive or close  If the margins are microscopically positive, radiation should be given postoperatively [1,14,15]

Discussion : Post treatment Imaging  Increasing signal intensity on T2-weighted MR images may

be seen within the synovial sarcoma after chemotherapy or radiation therapy but does not mean recurrence  Tumor size may also show a reduction in response to this

therapy  Oedema surrounding the tumour, typically not a

significant feature before therapy, may also develop subsequent to adjuvant treatment

Discussion : Local recurrence and Metastasis  The clinical course of synovial sarcoma is characterized by a high rate of

local recurrence and metastatic disease.  Local recurrence following resection occurs in 30%– 50% of patients, and

distant metastasis in 41% [16]  The most frequent metastatic site is the lung (94%), followed by lymph

nodes (4%–18%) and bone (8%–11%)  Metastases are present in 16%–25% of patients at their initial presentation

[17]  The majority of metastases occur within the first 2–5 years after treatment

 Late metastases may occur up to 26 years after the initial diagnosis, which

reduces the 10-year versus 5-year survival rates

Discussion : Prognosis factors Clinical and pathologic factors having prognostic significance :  Age: < 15–20 years is also associated with a better long-term prognosis  Location in the extremities: more favourable prognosis  Tumour size: greater than 5 cm at presentation has the greatest impact

(64% vs 26% 5 years survival rates)  The presence of extensive calcifications: suggests improved long-term survival, with 5-year survival rates of 82% and decreased rates of local recurrence (32%) and metastatic disease (29%) (1,16,18,19)  Other factors:  Degree of differenciation

 high nuclear grade  More recently, the gene fusion type SYT-SSX2 (more common in

monophasic lesions) has been associated with an improved prognosis (compared with that for SYT-SSX1, and an 89% metastasis-free survival).

CONCLUSION  Synovial sarcoma is the fourth most common malignant primary

soft-tissue neoplasm

 Although the radiographic and ultrasonographic signs of

synovial sarcoma are not specific, the presence of a soft-tissue mass, nearby a joint in a young patient is very suggestive of this diagnosis

 MRI is the method of choice for staging extent and surgical

planning

 Local recurrence and metastatic disease are common and

prognosis is guarded

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