Primary pleuropulmonary synovial sarcoma: reappraisal of a recently described anatomic subset

Primary pleuropulmonary synovial sarcoma (SS) is a rare neoplasm and a recently recognized anatomic subset. Its clinicopathologic attributes are not yet well defined.

In this study, the clinical and histopathologic features of 12 SS arising in the lung and/or pleura were analyzed.

The neoplasms occurred in 7 men and 5 women, 20-72 years old (median, 31 years), were well circumscribed with a mean size of 7.2 cm, and involved either lung (9 cases), pleura (2 cases), or both (1 case). All the tumors were of monophasic type. Nine showed a classic spindle cell pattern, and three showed predominantly poorly differentiated features. All but one case showed at least focal positivity for epithelial membrane antigen (EMA), a finding characteristic of this tumor. The lack of EMA staining in one case, proven by electron microscopy to be SS, was attributed to the scarcity of material available for immunohistochemical stains. The diagnosis was proven cytogenetically in three cases. Within 2 years, local recurrence developed in 8 patients (75%), 3 of whom developed metastasis (25%). Five patients died of their disease within 2.5 years, 4 of them from uncontrolled local disease.

The authors conclude that pleuropulmonary SS, although rare, represents a distinct anatomic subset having pathologic features similar to those of its soft tissue counterpart. Its clinical behavior appears more aggressive, perhaps because of relatively later presentation combined with the difficulty in obtaining a wide surgical margin.