Retroperitoneal synovial sarcoma: a clinicopathological study of 6 cases

Synovial sarcoma (SS) arising in the retroperitoneum is a rare tumor. In this location it can be confused with other biphasic tumors and with other spindle and round cell sarcomas. We report 6 cases of SSs with emphasis on their clinicopathological findings.

Six cases were studied, diagnosed as primary retroperitoneal SSs. Clinical, radiological and pathological findings were included in the study. Follow-up information was available in 5 out of 6 cases.

The cases consisted of 5 males and 1 female (aged 27-42 years, median 34), who complained preoperatively for pain in the abdominal region (n=4) and dysuria (n=2). Clinical examination was negative. Abdominal X-ray showed a suspicious mass in 4 cases and computed tomography (CT) revealed the tumor mass in all cases. Surgical removal of the tumor was performed. Tumors ranged in size from 6.5 to 14 cm (median 11); histologically, all tumors were biphasic and 1 had poorly differentiated areas. Sarcomas were of high grade (n=3) and intermediate grade of malignancy (n=3). Immunohistochemical stains for cytokeratins AE1/AE3, CAM5.2, S-100, CD34, EMA, SMA and CD99 were performed. All tumors recurred or metastasized within the abdomen. Four patients died of disease within 8-38 months.

Retroperitoneal SSs are very rare neoplasms that attain a large size, are difficult to excise and recur locally. Metastatic potential is low; however, mortality is very high.