Synovial sarcomas (SS) are tumors of mesenchymal and epithelial origin and is the fourth most common type of soft-tissue sarcoma,
accounting for 8%–10.5% of all primary soft-tissue sarcomas.
SS occur in any age,
but mostly in adolescents and young adults (15–40 years of age).
They are the most common sarcoma subtype in the adolescent population.
Despite its name,
is not related to synovial tissue and does not commonly arise in an intraarticular location,
but usually occurs near joints.
SS can appear in almost any anatomical site.
Often affects the extremities (80%–95% of cases): the most common being the knee,
in the popliteal fossa.
The large minority of cases are located in the upper extremities,
but they present the same imaging features.
Patients usually present themselves with a progressive slow growing palpable mass or swelling.
The average duration of symptoms is 2– 4 years,
but can vary from weeks to decades.
Diagnosis is made mostly through histologic analysis.
There are three main histologic subtypes of synovial sarcoma: biphasic,
monophasic,
and poorly differentiated.
Biphasic tumors being those with both mesenchymal and epithelial components.
It has been discovered that SS are marked by the presence of a pathognomonic translocation between chromosomes X and 18,
t(X;18)(p11.2;q11.2),
that appear in more than 95% of patients and represents an important diagnostic tool.
SS is generally considered a high-grade sarcoma,
marked by a poor prognosis,
with an expected 5-year survival in adult patients ranging from 50% to 60% and a 5-year metastatic disease-free survival (DFS) ranging from 40% to 60%.
SS show high metastatic potential.
Tumor size,
young age,
tumors not from the extremities and response to first-line chemotherapy are good prognostic indicators.
Treatment is usually done by resection of the tumor,
with or without neoadjuvant chemotherapy,
followed by an adjuvant chemotherapy regimen.
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The role of imaging is planning the surgical procedure,
initial staging of the disease,
either locally and by identifying distant metastasis,
as well as post-treatment follow-up.