2023 Volume 62 Issue 3 Pages 151-158
Background : We report a case of mesothelioma in which cytology revealed numerous signet ring cells, and it was a challenge to differentiate the case from adenocarcinoma. In our cytological study reported herein, we compared the cells for which differentiation was a problem that were difficult to identify accurately. We also discuss the relevant literature and gene mutations in the signet ring cells.
Case : The patient was a 65-year-old Japanese male with a history of asbestos exposure. PET-CT was suggestive of pleural mesothelioma and pleural fluid cytology was performed. Many of the cells showed vacuolated cytoplasm and could not be clearly differentiated from adenocarcinoma cells. However, mesothelioma was suspected based on the mixture of cells showing combination of nuclear findings, microvilli findings, and metachromasia. Immunohistochemical staining was performed on the cell block prepared at the same time, and based on the findings, we made a final diagnosis of mesothelioma.
Conclusion : There is a morphological difference are morphological differences between the signet ring cells found in adenocarcinoma and those found in mesothelioma. We suggest that based on the findings in the present case and our literature review, signet ring cells showing metachromasia are characteristic of mesothelioma. Comparison of gene mutations with the surrounding mesothelioma cells in the present case indicated that the signet ring cells also undergo gene mutations similar to those occurring in the mesothelioma cells.
