Patients ranged in age from 21 to 80 years (mean age,
52 years).
Men and women were affected almost equally (M/F ratio,
1:1,4).
The most common symptom at presentation was a palpable soft-tissue mass (thirteen of twenty two patients).
Four patients reported swelling,
three experienced local pain,
one patient reported pneumothorax,
and one had constitutional syndrome.
The most frequent locations were,
in this order: foot (6/22),
knee (3/22),
thigh (3/22),
armpit (3/22),
neck (2/22),
thorax (2/22),
forearm (2/22) and scapular region (1/22).
Metastases data of four patients were not available.
Eleven of eighteen patients developed metastases (61%),
primarily to the lungs,
and seven had not metastases (39%).
Metastases location was lung in 89% of cases.
72.7% of women and 42.9% of men with synovial sarcoma had metastases.
75% (3/4) of lesions showing calcifications on X-ray had metastases.
Metastases were present in 71.4% of cases of synovial sarcoma in a distal location,
and when it was proximal,
44.4% had metastases.
63.6% of metastatic synovial sarcomas and 38.6% of non-metastatic lesions were heterogeneous on MR.
75% of metastatic lesions had heterogeneous enhancement after the administration of Gadolinium,
and the resting 25% had homogeneous enhancement.
All patients who presented a poorly differentiated or biphasic synovial sarcoma (two and one patient,
respectively),
and 60% who presented a monophasic lesion (six patients) had metastases.
We lost seven patients in this parameter.
75% of metastatic synovial sarcoma were grade 3 (three patients),
and 25% were grade 2 (one patient).
The mean follow up for disease free survival time (DSF) was 25 months (range,
3-213 months).
The estimated 1-,
2- and 5- year DSF rates were 89%,
66% and 52%,
respectively.
The estimated 1-,
2-,
and 5-year survival rates (OS) were 100%,
92%,
and 53%,
respectively (the mean follow-up for surviving patients was 8 years,
with a range of 4 months – 16 years).
Patients with localized synovial sarcomas less than 5 cm in longest diameter had a survival at 5 years of 60 % compared with a 5 -year survival of 48% for patients with sarcomas greater than 5 cm (Hazard Ratio = 2.66).
The mean size of the primary tumor on imaging was 5.1 cm in patients without metastasis and 6.4 cm en patients with metastases.
The lower extremity was the most common involved.
The duration of symptoms ranges from one month to 23 years with a mean time of 12 months.
All patients underwent surgery,
in association with adjuvant chemotherapy in nine cases,
and post-operative radiotherapy in twelve cases.
Histological subtypes could be checked in 21 of 22 patients.
Histological subtypes included monophasic synovial sarcoma in eleven cases,
biphasic synovial sarcoma in two cases and poorly differentiated synovial sarcoma in two cases.
Two of eleven cases were grade 1,
three of eleven were grade 2,
and five of eleven were grade 3 (50%).
Inmunohistochemical mutation SYT + was presented in 6 of eight patients studied (75%) and two of eight were SYT -.
Radiologic findings
We reviewed conventional radiographs in ten cases (45%),
ultrasound in nine cases (40.9%),
CT images in four cases (18%),
MR images in sixteen cases (72.7 %) and PET/CT in two cases (9%). Those patients who did not have MR images presented an axial localization of the tumor: head and neck or chest.
PET/CT was performed after surgical resection of the tumor.
On conventional radiographs (CR) four of ten lesions had calcifications (40%).
Only one lesion showed bone invasion and erosion.
In all cases,
plain radiograph showed non-specific findings or a slight soft-tissue enlargement.
Ultrasound images showed a hipoecoic ovoid-shape mass in all cases studied by ultrasound (nine of nine patients).
In two cases,
US images demonstrated a lesion with heterogeneous echogenicity.
In seven cases,
the tumor has a homogeneous echogenicity.
CT images were performed in those patients who presented with systemic,
chest or proximal extremity symptoms and the first clinical impression was not a soft-tissue tumor.
These lesions were localized in neck,
mediastinum,
scapular region and hip,
respectively.
In two cases,
CT scan revealed the involvement of underlying bone by showing periosteal reaction.
Features of MRI
T1-weighted and T2-weighted MR images of sixteen lesions revealed that twelve were located < 5 cm from the nearest joint (87%),
eleven were intermuscular masses (69%),
and thirteen (81%) well-defined lesions,
with only three(19%) unclearly defined round lesions.
In a similar percentage,
the T2-weighted MR images demonstrated a lesion with internally septation (56 %) and no septation (44%). Eleven (69%) cases demonstrated split fat sign,
and only one case revealed fluid-fluid levels (6%).
Four cases (25%) demonstrated a hyperintensive T1 signal,
suggesting hemorrhage.
The majority of the lesions (75%) were heterogeneous on MRI,
being homogeneous only four of them.
50% of lesions showed central necrosis,
and the other 50% not.
Only one case revealed neural compromise.
Ten cases had vessels inside the lesion (62.5%).
Perilesional oedema was present in five cases of sixteen (31.2%).
All cases demonstrated hyperintensity on T2-weighted images. Twelve of sixteen lesions showed hypointensive T1 signal (75%),
and four of them demonstrated an isointensive T1 signal (25%).
Contrast-enhanced images revealed that 50% of the lesions had a heterogeneous solid enhancement (eight of sixteen),
three of them had a homogeneous solid enhancement,
and two of sixteen showed peripheral enhancement.
Overall,
five lesions of sixteen (31.2%) showed triple sign and three of sixteen (18.7%) showed grape sign.
Some predictors of poor prognosis on MRI were the presence of calcifications and irregular margins.
Patients with well defined margins lesion on MR synovial sarcomas had a survival at 2 years of 80 % compared with a 2 -year survival of 33% for patients with sarcomas showing poorly defined margins (Hazard Ratio = 4.5).
Patients with localized synovial sarcomas without calcifications on MRI had a survival at 3 years of 48 % compared with no patients alive at 3 -year survival of those showing calcifications.
Metastases were present in 77.8% of patients with lesions showing heterogeneity on MR,
and in 50% of patients with lesions showing homogeneity.
Patients with necrotic lesion on MR had survival at 2 years of 68%,
in the same percentage than those not showing necrosis.
Those patients with lesions showing triple sign and grape sign on MRI had a survival at 2 years of 75% and 50%,
respectively,
compared with a 2-year survival of 67% and 63% for patients with sarcomas not showing triple sign.