Supplementary Material for: High-grade sarcoma of the pulmonary artery that mimicked a pulmonary embolism in a 39-year-old patient with recurrent miscarriages: a case report

Introduction
Primary pulmonary artery sarcoma (PPAS) is a rare malignancy with a poor prognosis, undefined treatment guidelines, and is often mistaken for a pulmonary embolism based on similar clinical presentation and radiographic findings.

Case Presentation
We present a case of a 39-year-old female with a past medical history of recurrent miscarriages who presented with a chief complaint of dyspnea. Due to a history of recurrent miscarriages, a predisposing coagulopathic condition was suspected for a pulmonary embolism. A V/Q scan showed high probability for a pulmonary embolism with bilateral perfusion defects. Subsequent CT angiographic imaging of the chest was read as positive for a massive pulmonary embolism. The patient was transferred to the medical ICU for tPA administration, but developed worsening hypoxic respiratory failure and was transferred to an outside hospital for expert surgical consultation and thrombectomy. Intraoperative reports during thrombectomy commented on a mass within the pulmonary artery. Subsequent pathology showed a high-grade sarcoma. The patient was started on adjuvant chemotherapy with doxorubicin, ifosfomide, and MESNA, however, due to multiple comorbidities, the patient ultimately succumbed to her illness.

Conclusion
This case underscores the diagnostic difficulty in distinguishing pulmonary artery sarcomas from a pulmonary embolism, especially in the presence of other confounders and biases.

引言
原发性肺动脉肉瘤（Primary pulmonary artery sarcoma, PPAS）是一种罕见的恶性肿瘤，预后较差，治疗指南尚未明确，且因其临床表现与影像学特征与肺栓塞（Pulmonary Embolism）高度相似，常被误诊为肺栓塞。

病例报告
本例为1例39岁女性患者，既往有复发性流产（Recurrent Miscarriages）病史，以呼吸困难（Dyspnea）为主诉就诊。鉴于患者存在复发性流产病史，临床首先怀疑其存在易栓症，进而考虑为肺栓塞。肺通气/灌注显像（Ventilation-Perfusion scan, V/Q scan）结果提示为高概率肺栓塞，伴双侧灌注缺损。后续胸部CT血管造影检查结果判定为大面积肺栓塞。患者被转入内科重症监护室接受组织型纤溶酶原激活剂（Tissue Plasminogen Activator, tPA）治疗，但病情进展为低氧性呼吸衰竭加重，随后被转至外院寻求外科专家会诊并实施血栓切除术。血栓切除术术中记录显示肺动脉内存在肿物。后续病理学检查结果提示为高级别肉瘤。患者随后接受了多柔比星、异环磷酰胺（Ifosfamide）与美司钠（MESNA）组成的辅助化疗方案，但因合并多种基础疾病，最终因病情恶化死亡。

结论
本病例凸显了肺动脉肉瘤与肺栓塞的鉴别诊断难度，尤其当存在其他混杂因素（Confounders）与认知偏倚（Biases）时，该鉴别尤为困难。