Imaging features of primary and recurrent intrathoracic synovial sarcoma: A single-institute experience

Objective: The objective was to study the imaging features of primary and metastatic intrathoracic synovial sarcoma (ISS). Materials and methods: We reviewed the imaging of 42 patients with ISS (31 pleural, 7 intrapulmonary, 4 mediastinal), with baseline imaging of 19 patients and follow-up imaging in all. Results: Primary tumors (n=19) were well circumscribed (15/19), homogeneous or heterogeneously enhancing, with mean size 9.1 cm (range: 1.8-25 cm). Recurrent/metastatic disease developed in 28/42 patients (67%). Lung was the most common site of metastases (21/28), with most of them predominantly pleural (11/21). On pathology, 30 patients had monophasic tumors, and 6 each had biphasic tumors and poorly differentiated tumors. Conclusion: Intrathoracic SS most commonly presents as a large heterogeneous pleural mass without associated adenopathy. Lung metastases are often pleural based and ipsilateral.