Malignant tumors are risk factors for a pulmonary embolism (PE), and a PE caused by a tumor is not uncommon. Primary pleural squamous cell carcinoma (PPSCC) is a rare malignancy; thus, a related PE is extremely rare. A previously healthy 49-year-old female patient was admitted to Northern Jiangsu People’s Hospital owing to chest tightness, cough, and breathing difficulty that persisted for 3 days. Following admission, a computed tomography (CT) pulmonary angiography revealed an embolism in the main pulmonary artery, upper and lower pulmonary artery branch. The patient was treated with alteplase, warfarin, and antibiotics. Over the following year, she experienced recurrent chest pain and tightness and breathing difficulty, with multiple CT pulmonary angiography revealing thrombosis in the right and left main pulmonary artery. No abnormalities were observed in surrogate markers of autoimmune diseases, tumor antigen testing, or ultrasonography; thus, the cause of recurrent PE was not identified. Subsequently, a positron emission tomography-computed tomography (PET-CT) examination revealed diffuse heterogeneous thickening of the right pleura and substantially increased glucose metabolism. A CT-guided pleural biopsy was performed, and histopathological examination of the pleura eventually revealed a diagnosis of PPSCC. PPSCC is a rare tumor that lacks specific clinical manifestations and is difficult to detect with imaging techniques. The occurrence of PE as the primary manifesting symptom in a patient with PPSCC is extremely rare. Thus, malignant tumors should be considered in patients with no risk factors for PE and/or in those with recurrent PE. An immediate diagnosis and adequate intervention can be achieved with increased awareness of this diagnosis and subsequent related examinations.

中文翻译：

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反复肺栓塞的罕见原因：原发性胸膜鳞癌一例并文献复习

恶性肿瘤是发生肺栓塞（PE）的危险因素，由肿瘤引起的PE并不少见。原发性胸膜鳞状细胞癌（PPSCC）是一种罕见的恶性肿瘤。因此，相关的PE极为罕见。一名先前健康的49岁女性患者因胸闷，咳嗽和呼吸困难持续了3天，因此被送进了苏北人民医院。入院后，计算机断层扫描（CT）肺血管造影显示主肺动脉，上，下肺动脉分支发生栓塞。患者接受阿替普酶，华法林和抗生素治疗。在接下来的一年中，她经历了反复出现的胸痛，气密和呼吸困难，多次CT肺血管造影显示左右主肺动脉有血栓形成。在自身免疫性疾病，肿瘤抗原检测或超声检查的替代指标中未观察到异常；因此，未发现复发性PE的原因。随后，正电子发射断层扫描计算机断层扫描（PET-CT）检查显示右胸膜弥漫性异质增厚，葡萄糖代谢显着增加。进行了CT引导的胸膜活检，对胸膜的组织病理学检查最终显示诊断为PPSCC。PPSCC是一种罕见的肿瘤，缺乏特定的临床表现，并且难以通过成像技术进行检测。PPSCC患​​者中PE作为主要表现症状的发生极为罕见。因此，对于没有PE危险因素的患者和/或PE复发的患者，应考虑恶性肿瘤。