What is Synovial Sarcoma?
The name "synovial sarcoma" was coined early in the
20th century, as some researchers thought that the
microscopic similarity of some tumors to
synovial, and its propensity to arise adjacent to
joints, indicated a synovial origin; however, the
actual cells from which the tumour develops are
unknown and not necessarily synovial.
Synovial sarcoma is a misnomer because this
malignancy is only rarely found within joints and it
has no immunocytochemical relationship to the CK-
negative normal synovium
What is Synovial Sarcoma?
This is a rare and aggressive soft tissue malignant tumor that
begins near joints in the body.
Typically around ankle and knee joint.
Around shoulder and hip joint.
Other site- including neck (particularly the retropharyngeal
area), anterior abdominal wall, abdominal
cavity, retroperitoneum, mediastinum , blood vessels, nerves.
Lately, it has become evident that the distribution of this
tumor is even wider, with cases reported in the oral cavity
salivary glands, lung, gastrointestinal tract , kidney, prostate
Who is Affected?
Age- 30 yr.
Male: Female- 1.2
The exact etiology of Synovial sarcomas is unknown.
What is known is that many Synovial sarcoma cells
are characterized by a chromosomal translocation
that fuses the SYT gene from chromosome 18 to
either the SSX1 or the SSX2 gene.
The fusion proteins SYT-SSX1 and SYT-SSX2 are
believed to function as abnormal transcriptional
regulators that result in
Either activation of proto-oncogenes or inhibition of
tumor suppressor genes.
probes can reliably
identify the SYT
disruption in synovial
probes, one in the red
and one in the green
spectrum stain the
18q11.2 region. The
normal and abnormal
(broken apart) one can
be seen here
The most common symptom experienced is a
swelling or mass that may be accompanied by pain
In a few cases it has been noted that pain or
tenderness was present for several years even
though a mass could not be felt.
Limping or difficulty using legs, arms, hands or
feet have been reported.
circumscribed, firm, and
grayish pink. Focal
calcification is frequent
and may be detected
located in the hands or
feet, it may have
Biphasic tumor composed of sharply segregated
epithelial and sarcomatous components
The epithelial areas usually appear in the form of
gland-like spaces lined by cuboidal or columnar
cells, but can also present as solid nests of large pale
cells. It is exceptional for this component to exhibit
The sarcomatous component is made up of spindle
cells with a fibroblast-like appearance.
It tends to be hypercellular but with a relatively
monotonous appearance, plump nuclei, a focally
whorled pattern, distinct lobulation or fasciculation,,
Large number of mast cells
calcification, and When the calcification is
particularly heavy, the term calcifying synovial
sarcoma has been used.
osseous metaplasia can be present.
Typical biphasic appearance of synovial sarcoma
Calcifying synovial sarcoma. , Radiographic
appearance of tumor located in popliteal space
Monophasic synovial sarcoma is composed of only
one of the two components.
In the large majority of cases, this applies to the
spindle cell sarcomatous component, which is easily
misdiagnosed as fibrosarcoma,hemangiopericytoma.
A search for epithelial-looking foci should be carried
out in these situations, as well as a thorough
immunohistochemical (and possibly molecular)
Theoretically, a monophasic form of synovial
sarcoma composed only of the epithelial elements of
the tumor should also exist.
The fact that in some neoplasms the glandular
elements are so prominent as to simulate a
metastatic adenocarcinoma cannot be denied.
However, the existence of a pure form of
monophasic epithelial synovial sarcoma has yet to be
convincingly demonstrated at the
A poorly differentiated form of synovial sarcoma is
being increasingly recognized, characterized by a
greater degree of cellularity, atypia, and mitotic
The tumor cells may be spindle, small, or large and
clear, Here too, immunohistochemical and
particularly cytogenetic/molecular confirmation
Monophasic synovial sarcoma. The tumor is
hypercellular but remarkably monomorphic
Special stains: Histochemistry- Secretions within
the epithelial cell and pseudoglandular spaces
are PAS positive and diastase resistant, alcian
blue and mucicarmine positive.
The stromal mucin secreted by the spindle cells
are alcian blue positive but PAS negative.
Reticulin stain demonstrate the biphasic pattern
of the tumor. Nests of plump rounded cells are
highlighted by the reticulin stain.]
In Synovial sarcoma there is usually
coexpression of mesenchymal (vimentin) and
epithelial markers (cytokeratin & EMA).
The following immuno markers are useful in the
- Cytokeratin (+)
Only synovial sarcoma is positive
with cytokeratins 7 & 19 , other soft tissue
sarcomas incl. synovial sarcoma is positive with
cytokeratin 8 & 18 ;
- EMA (+) ,
- Vimentin (+),
in some cases
S100 protein (+)
, CD99 (+) .
- bcl-2 (+)
Application of a panel of
immunohistochemical markers is suggested
to avoid diagnostic pitfalls.
positivity is found near
the periphery of the
lesion. Up to 97% of
cases of synovial
sarcoma will have
CD99, the product of
the MIC2 gene is
seen in a
and can be detected
in up to 70% of
, the bcl-2 protein
can be demonstrated
strongly, as here.
try stains help
diagnosis of synovial
Synovial sarcoma is associated with
chromosomal translocation t(x ;18) (p11.2 ;
Synovial sarcoma can recur locally .
Metastasize distantly, particularly to the lung and
The incidence of nodal metastases is in the range of
Better for the synovial sarcomas associated with
heavy calcification (calcifying synovial sarcoma),
Age (better in young patients),
Site (better for distal lesions),
SIZE-better for tumors less than 5 cm in diameter),
Status of the surgical margins,
Mitotic activity (better for tumors having fewer than
15 mitoses per 10 high-power fields),
Necrosis (worse for tumors having tumor necrosis of
more than 50%),
Rhabdoid cells (worse when present),
Dysadherin expression (worse when
present, indicating E-cadherin dysfunction),
DNA ploidy pattern (worse for aneuploid tumors).[
Synovial sarcomas may be treated by using the
following medical approaches…
Complete surgical excision of the tumor, nearby
muscle and lymph nodes is the best way of treating
Depending on the location and size of the tumor, it
may be necessary to remove all or part of a limb.
Radiation is often used in conjunction with surgery
to kill cancer cells.
It can be given before surgery in order to shrink a
tumor or afterwards to kill any remaining cancer
On rare occasions radiation alone has been used for
treatment of the primary tumor.
Chemotherapy has been proven highly effective with
treating this form of cancer and it may be
administered in one of the following ways…
As a pill to swallow
As an injection into the muscle or fat tissue
Intravenously is the most common form of delivery for