Mediastinal undifferentiated pleomorphic sarcoma with pleural effusion cytopathologically misdiagnosed as epithelial malignant pleural mesothelioma: An autopsy case report

• Main Authors: Kinnosuke Matsumoto, Yukihiro Nakamura, Yuji Inagaki, Yoshihiko Taniguchi, Akihiro Tamiya, Yoshinobu Matsuda, Takahiko Kasai, Shinji Atagi
• Format: Article
• Language: English
• Published: Wiley 2021-04-01
• Series: Thoracic Cancer
• Subjects: cell block; malignant pleural mesothelioma; mediastinum; pleural effusion; undifferentiated pleomorphic sarcoma
• Online Access: https://doi.org/10.1111/1759-7714.13898

Abstract Undifferentiated pleomorphic sarcoma (UPS) is a new disease in the World Health Organization's classification of tumors of soft tissue and bone published in 2013. Primary mediastinal UPS is rare, especially with pleural effusion. Herein, we describe the pathological findings of pleural effusion followed by mediastinal UPS, which was initially misdiagnosed as epithelial malignant pleural mesothelioma (MPM). The cytopathological findings of the pleural effusion cell block often contribute to the diagnosis of various malignant tumors. However, these findings may lead to misdiagnosis of highly invasive mediastinal tumors such as UPS. A biopsy for primary mediastinal lesions should be performed because MPM rarely mimics mediastinal tumors with pleural effusion.