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.