The role of diagnostic imaging in synovial sarcoma. Our experience

Synovial sarcoma is a rare malignant mesenchymal tumour of soft tissues. It accounts for 8-10% of all soft-tissue sarcomas. The clinical symptoms at onset are often subtle and the course of the disease is slow. Therefore, diagnostic imaging is essential for the early diagnosis of a malignant tumoral lesion. The aim of this study was to assess the role and usefulness of the different imaging procedures in the diagnosis of synovial sarcoma and to present their findings.

Between 1985 and 2002, we retrospectively reviewed 35 patients (21 men and 14 women, aged 14-66 years) with synovial sarcoma treated in the Orthopaedic Oncological Surgery Division of our hospital. All patients had previously undergone conventional radiography, B-mode ultrasound, computed tomography and magnetic resonance imaging.

Conventional radiography showed indirect signs of the neoplasm including soft-tissue swelling, calcifications and bone erosions. Ultrasound allowed the detection of focal nodular lesions but was non-specific in distinguishing malignant features. CT after intravenous injection of contrast medium demonstrated inhomogeneous enhancement in 90% of cases, suggesting an alteration in tumour microcirculation. In all cases examined, MRI enabled detection of the intrinsic structural alterations of the mass indicative of an aggressive lesion.

Contrast-enhanced CT and MRI provide useful information on the intrinsic structure of the neoplasm, suggesting a presumptive diagnosis. Furthermore, they are necessary for tumour staging, surgical planning and follow-up. The definitive diagnosis is provided by biopsy and histology.