2018 Volume 57 Issue 2 Pages 129-135
Background : Myoepithelial carcinoma (MC) of the soft tissue is very rare, and its cytological/histological diagnosis is challenging.
Case : A Japanese man in his late teens was referred to our institution for a painless mass in the left shoulder, that had first been noticed 10 years previously. The mass had increased rapidly in size during the previous six months. Open biopsy and wide resection were performed. Squash preparation cytology obtained at open biopsy showed that the tumor was composed of small round tumor cells, with some focal cluster formation, including occasional perivascular clustering. Rosette-like structures were also seen. Cytologically, Ewing sarcoma was suspected. Histologically, the tumor was composed of tumor cells proliferating in solid nests, with focal reticular pattern formation, in a myxoid and hyalinized stroma. Based on these findings, considered together with the findings of immunohistochemical and genetic analyses, the tumor was diagnosed as MC of the soft tissue.
Conclusion : Since MC may exhibit different features in cytology samples taken from different sites, it may be difficult to make a precise diagnosis. When round tumor cells are detected in cytology samples of the soft tissue, MC should be considered, taking into account the clinical and genetic findings.
