# Synovial Sarcoma of the Extremities: A Literature Review
## 2 Diagnosis
### Imaging Examinations  
X-ray: Simple X-rays are not sensitive enough for the diagnosis of SS. Usually, an X-ray is the first imaging study performed as a routine procedure in the presence of an overgrown tumoral mass in an extremity. Calcifications, which can mimic myositis ossificans, and bone involvement (erosions, osteolysis) may be observed on plain X-rays (Figure 1).  
Magnetic resonance imaging (MRI) with contrast should be considered for tumors exceeding 2-3 cm and is probably the imaging method of choice for synovial sarcomas. MRI will provide valuable information regarding the extent of the tumor and the relationship with the surrounding anatomical structures; the use of a gadolinium contrast will enhance the amount of information that can be obtained since it is able to differentiate between hemorrhagic areas and solid tumoral tissue.  
The T2 sequences are more specific for the diagnosis of soft tissue sarcomas and can reveal an inhomogeneous tumor, mainly with a hyperintense signal, in contrast with muscles, and the specific \"triple sign\" is present, representing a mixture of solid parts (medium hemorrhage and/or necrosis (high signal intensity) and calcifications or/and fibrotic areas (low signal intensity). The heterogeneity is completed by the presence of cystic parts with an aspect of fluid-fluid levels due to blood sedimentation (Figures 2 and 3).  
Figure 1: Synovial sarcoma, F, 40 YO—radiological AP view of the right hip and proximal thigh (prior to CT exam) reveals the presence of soft tissue calcifications medial to the lesser trochanter.  
Figure 2: A 40-year old female patient with synovial sarcoma. Image represents an axial MRI of the proximal right thigh—axial T2 FSE (fast spin echo) and FATSAT (fat saturation). There is an increased diameter of the right thigh because of a soft tissue mass (thin arrows), where an inhomogeneous mixture of solid and cystic areas is shown (block arrow).  
Computed tomography (CT) is usually performed either if the MRI is contraindicated (e.g., due to the presence of orthopedic implants), is unavailable or if the radiologists need additional information regarding the local bone involvement or better visualization of the intratumoral calcifications (Figures 4-6).  
Figure 4: Axial CT-scan: evident enlargement of the right thigh; heterogeneous soft-tissue mass with calcifications, adjacent fat infiltration and skin thickening— synovial sarcoma, M, 26 YO patient.  
Figure 5: Synovial sarcoma, F, 31 YO patient—CT image, axial section: soft-tissue mass with heterogeneous content, showing necrotic areas alternating with calcifications and cystic areas.  
Figure 3: Same patient as in Figures 1 and 2, MR image, coronal T2 STIR (short-time inversion recovery): heterogeneous soft tissue mass showing a mixture of solid areas (line arrow), hemorrhage and/or necrosis (block arrow), calcifications or fibrosis, cystic elements and infiltration of adjacent fat. Furthermore, fluid–fluid levels (block arrow) can be observed in this figure.  
Other imaging examinations may be required. For example, a bone scan may be useful in detecting possible metastatic lesions or an Angio-CT may be requested by the oncologic surgeon, especially for deep synovial sarcomas in order to understand the relationship of the tumor with the neurovascular structures for appropriate preoperative planning (Figure 7).