Abstract
Background : We report the cytomorphologic features of primary intra-abdominal biphasic synovial sarcoma (SS) in cytology of peritoneal washings and tumor imprint cytology.
Case : A Japanese woman in her 50’s underwent complete removal of a large intra-abdominal tumor measuring about 15 cm in size. Histologically, two components were observed : an epithelioid component, with the cells forming rounded nests, and a stromal component, with the cells arranged in sheets and fascicles. Immunohistochemistry revealed positive staining for EMA, AE1/AE3, CK7, vimentin and calretinin. Based on the findings, the tumor was diagnosed as a biphasic SS arising from the abdominal cavity ; the tumor was detected by RT-PCT as expressing the SYT-SSX1 fusion gene. In both cytology of the peritoneal washings and imprint cytology, two types of tumor cells were observed : scattered atypical spindle-shaped cells with cigar-shaped nuclei, nuclear infoldings and/or intra-nuclear inclusions, and atypical epithelioid cells with round nuclei, a high N/C ratio, nuclear moldings and paired cells.
Conclusion : The appearance of both atypical spindle-shaped and epithelioid cells in cytology of peritoneal washings and imprint cytology is useful for accurate diagnosis of biphasic SS. Immunohistochemistry and genomic analysis are necessary for diagnosing and distinguishing SS from other malignancies.
