A case of Ewing sarcoma/primitive neuroectodermal tumor of the uterine cervix: Comparison between stamp cytology and liquid-based cytology

Background : We report a rare case of Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), assumed to arise from the uterine cervix. Case : A 30-year-old woman presented to us with the complaint excessive menstrual and irregular vaginal bleeding. A surgically excised specimen suggested the diagnosis of ES/PNET, both histologically and immunohistochemically. Stamp cytology revealed a large number of atypical small round cells, scattered or in focal clusters, with a high N/C ratio, hyperchromatic nuclei, a fine to coarse granular chromatic pattern and small nucleoli. Rosette-like structures were identified in parts of the clusters, suggesting neuroectodermal differentiation. However, almost all atypical cells from the LBC specimen had a fine chromatic pattern, and showed a different pattern from that of the stamp cytology. Conclusion : The granular chromatic pattern is important for suspecting neuroectodermal or neuroendocrine differentiation. The tumor cells may lack the characteristic chromatic pattern, especially when processed for LBC. A liquid-based material is available for immunocytochemical staining, and by careful evaluation of the cytological and immunocytochemical findings, the correct differential diagnosis can be reached.