Synovial Sarcoma in the Extremity: Diversity of Imaging Features for Diagnosis and Prognosis

Abstract

Synovial sarcomas are rare and highly aggressive soft-tissue sarcomas, primarily affecting adolescents and young adults aged 15–40 years. These tumors typically arise in the deep soft tissues, often near the large joints of the extremities. While the radiological features of these tumors are not definitely indicative, the presence of calcification in a soft-tissue mass (occurring in 30% of cases), adjacent to a joint, strongly suggests the diagnosis. Cross-sectional imaging characteristics play a crucial role in diagnosing synovial sarcomas. They often reveal significant characteristics such as multilobulation and pronounced heterogeneity (forming the “triple sign”), in addition to features like hemorrhage and fluid–fluid levels with septa (resulting in the “bowl of grapes” appearance). Nevertheless, the existence of non-aggressive features, such as gradual growth (with an average time to diagnosis of 2–4 years) and small size (initially measuring < 5 cm) with well-defined margins, can lead to an initial misclassification as a benign lesion. Larger size, older age, and higher tumor grade have been established as adverse predictive indicators for both local disease recurrence and the occurrence of metastasis. Recently, the prognostic importance of CT and MRI characteristics for synovial sarcomas was elucidated. These include factors like the absence of calcification, the presence of cystic components, hemorrhage, the bowl of grape sign, the triple sign, and intercompartmental extension. Wide surgical excision remains the established approach for definitive treatment. Gaining insight into and identifying the diverse range of presentations of synovial sarcomas, which correlate with the prognosis, might be helpful in achieving the optimal patient management.

Case report: Characteristics and nature of primary cardiac synovial sarcoma

“…In this patient, no tail signs were observed on MRI; however, caution is required because infiltration into the myocardium was observed macroscopically during surgery. The correlation between the triple sign and tail signs on MRI and prognosis is currently controversial ( 11 , 12 ). Patients with cardiac SS with suspected pericarditis on echocardiography and MRI have also been reported ( 13 ).…”

A 40-year-old female with swelling in left lower back

“…Globally, synovial sarcoma accounts for 8% of all primary soft-tissue malignancies, ranking fourth in frequency, succeeding undifferentiated pleomorphic sarcoma, liposarcoma, and rhabdomyosarcoma [3]. Approximately 70% of synovial sarcoma cases manifest around the knee joint [4]. Despite extensive investigations, the precise pathogenesis of synovial sarcoma remains unresolved.…”

Diffuse-Type Tenosynovial Giant Cell Tumor: What Are the Important Findings on the Initial and Follow-Up MRI?

“…In the diagnosis and treatment of TSGCT, MRI stands out as the most distinctive imaging technique [18]. The scanning protocol for soft tissue tumors should encompass, at a minimum, the following sequences: one set of T1-weighted images (T1WI) before the administration of gadolinium chelate, one set of T2-weighted images (T2WI) with or without fat-suppression techniques (such as fat-saturation, fluid sensitive, DIXON method, or short tau inversion recovery sequences), and one set of T1WI following the injection of gadolinium chelate, with fat-suppression [19]. Intravenous gadolinium contrast facilitates tumor detection and proves useful for follow-up after synovectomy [1].…”