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

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.

Pleomorphic undifferentiated sarcoma of the mediastinal thymus: A case report and literature review

“…The specific etiology of PUS is unknown and may be related to genetic aberrations and radiotherapy ( 10 ). To the best of our knowledge, only six cases of PUS were previously reported in the mediastinum ( 4 – 9 ) and the present one is the first report on PUSM. The present study aimed to report and analyzed this case along with the relevant literature review.…”

“…The mass was large, and the maximum diameter was 19 cm ( 4 ). An autopsy revealed that the tumor recurred into the pericardium, heart or great vessels ( 7 – 9 ). A physical examination of the present patient revealed that the mass was located in the anterior mediastinum with a clear boundary and irregular nodules with a maximum diameter of 5 cm.…”

“…A total of five subtypes of undifferentiated sarcomas are found in soft tissue, including pleomorphic, small round cell, spindle cell, epithelioid and non-specific sarcomas. Pleomorphic undifferentiated sarcoma (PUS) occurs mostly in middle-aged and elderly individuals, mostly in the soft tissues of limbs, trunk, head, and neck, and only six cases have been reported in the mediastinum ( 4 – 9 ). To the best of our knowledge, this is the first report on the presence of PUS in the mediastinal thymus site (PUSM).…”

Tislelizumab immunotherapy combined with chemotherapy in the treatment of a patient with primary anterior mediastinal undifferentiated pleomorphic sarcoma with high PD-L1 expression: A case report and literature review

“…Because UPS lacks special clinical manifestations in the early stage and features no specific changes on auxliary examinations, histopathological examination has become the gold standard for its diagnosis, presenting microscopically as a high-grade sarcoma without any specific differentiation direction. According to the majority of publications, UPS lacks specific immunohistochemical markers, which is an excluded diagnosis ( 14 ). Vimentin, WT-1, CD99, and EMA can be expressed in UPS ( 14 , 15 ).…”

“…According to the majority of publications, UPS lacks specific immunohistochemical markers, which is an excluded diagnosis ( 14 ). Vimentin, WT-1, CD99, and EMA can be expressed in UPS ( 14 , 15 ). However, Masamichi ( 16 ) et al.…”