Discussion:
Primary cardiac sarcoma are rare tumors and sarcoma of PV are very rare (4). Initial manifestation of these tumors are usually consist nonspecific symptoms of cardiopulmonary disease such as cough, dyspnea, chest pain, infrequently hemoptysis, pneumothorax and tamponade in cases with invasion to pericardium, mediastina or lung parenchyma (2-5). PA sarcoma can mimicking clinical and paraclinical findings of PTE and caused difficulties in early diagnosis and management. Some case reports representing misdiagnosis of PA sarcoma with PTE in early evaluating and for this reason the patients underwent thrombolytic therapies without any improvement and subsequent evaluations demonstrated malignant tumor of pulmonary artery (1,6,7).
Chest CT scan can help differentiate PA sarcoma from PTE by low-attenuation filling defect occupying the entire luminal diameter of the main or the proximal PA, expansion of any segment of the PA, and extraluminal extension of the tumor. These image features to be suggestive of PA sarcoma (8).
Magnetic resonance imaging (MRI) is also useful diagnostic method for distinguishing PASs and PTE. On MRI, low-intensity heterogeneous features on T1-weighted images and peripheral enhancement of the thickened pulmonary artery wall on T2-weighted images and after gadolinium injection have classically been thought to support a diagnosis of PA tumor (9).
Fluorodeoxyglucose / positron emission tomography (FDG/PET) CT can distinguish PASs from PTE based on the FDG uptake with maximum standardized uptake value (SUVmax) (SUVmax of PA sarcoma is higher than of PTE) (10).
Other characteristics, such as the absence of risk factors for deep vein thrombosis and high erythrocytes sedimentation rate should raise the suspicion of a process other than PTE (1).
The only method to definitely differentiate diagnosis between PASs and PTE is histopathology (3).
Surgery is the most effective treatment of PA sarcoma (1,7). Chemotherapy and radiotherapy are used and may provide longer survival, especially in patient with metastasis and incomplete resection. Endovascular stenting remains as palliative therapy for inoperable patient with obstructing tumors. Most cases of pulmonary sarcomas were diagnosed late in coarse of diseases and these made difficulties in surgical resection. Some reports shown that early diagnosis and surgical resection may provide longer survival (4-7).
Overall, PA sarcoma are very poor prognosis tumor because of late diagnosis and average of survival among reported case series were between 1.5 month to 12 months (5,11). Among patients reported have longer survival, RV function were preserved and didn’t mention significant increased PA pressure (5). Our patients had severe RV dysfunction in presentation and remaining of PA pressure severely high even after total resection of giant tumoral mass and in absence of any other mass or thrombosis in pulmonary arteries in pulmonary CT angiography after operation.
Patients with COVID-19 pneumonia and high D dimer value has higher prevalence PTE and myocarditis (12-15). Prior infection with COVID-19 pneumonia in our case maybe the other causes of RV failure and also masquerading sarcoma.
On the other hand, RV dysfunction due to cardiotoxicity of chemotherapy may considered as the other mechanism for progression of RV failure in our patient. Chemotherapy could induce impairment of RV structure, function and mechanistic (16,17).
Our case report emphasizes that PASs should always be included in the differential diagnosis of PTE especially if symptoms progress despite anticoagulation therapy (or any risk factor for deep vein thrombosis is not present). However, our patient underwent surgery immediately due to impaired hemodynamic and was diagnosed early compared to the time of hospitalization.