Synovial sarcoma metastatic to the parotid gland: A possible pitfall in salivary gland fine needle aspiration cytology. Report of a case with immunocytochemical and fluorescence in situ hybridization findings

摘要

We report one case of metastatic synovial sarcoma (SS) to the parotid gland in a 93-year-old male. The patient had undergone upper left pulmonary lobectomy with mediastinal lymphadenectomy for SS of the lung 5 years before. The cytopathologic presentation and the immunocytochemical findings on the FNA sample were suggestive of a spindle cell myoepithelioma, while a SYT rearrangement was identified by a FISH performed on a cytological smear of the lesion. The diagnosis was further confirmed also by positive immunocytochemical expression of TLE1 on a section from the obtained cell block. The cytologic and immunophenotypic findings are shortly discussed in view of the reported immunophenotypic inconsistency of SS and of its differential diagnosis with spindle cell myoepithelioma of the salivary glands. The importance of the recently described TLE1 staining and its close correlation to SYT rearrangement is briefly discussed.