[Primary synovial sarcoma of the lung].

In the biopsy material of a polypoid intrabronchial lesion of a 54-year-old male patient with radiologically established lung tumor, spindle-cell neoplasia was seen. No clear histogenetic classification of the submucous tumor process was possible. After resection of the right upper lobe of the lung, including the results of additional immunohistochemical analyses, the tumor was classified as biphasic synovial sarcoma. This was suggested mostly by immunohistochemical detection of the epithelial membrane antigene (EMA) and of vimentin. Extensive clinical examinations ruled out the possibility of a primary tumor with extrapulmonary localization. This case report shows the problems faced in correctly classifying the histogenesis or the direction of differentiation in extremely rare cases of primary pulmonary synovial sarcoma. Especially in small biopsy samples showing a submucous spindle-cell tumor of the lung, apart from frequent sarcoma metastases, the presence of primary synovial sarcoma of the lung has to be considered in the differential diagnosis.