An Unexpected Settler in the Right Ventricular Outflow Tract in Pulmonary artery sarcoma

doi:10.21203/rs.3.rs-2441562/v1

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Case Report

An Unexpected Settler in the Right Ventricular Outflow Tract in Pulmonary artery sarcoma

https://doi.org/10.21203/rs.3.rs-2441562/v1

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Pulmonary artery sarcoma (PAS) is a sporadic malignant tumor that mainly originates from the pulmonary arteries. However, PAS may also involve the right ventricular outflow tract, which may lead to obstruction, syncope, or sudden death. Early diagnosis is essential to prolonging survival and improving the quality of life. Herein, we report a case of a young female patient admitted for pulmonary malignancy and acute pulmonary embolism. The patient had a mass in her right ventricular outflow tract, which was detected by transthoracic echocardiography. Computed tomography and magnetic resonance imaging revealed the invasion depth and extent of the lesions. Surgical resection improved hemodynamics, and pathological and immunohistochemical tests confirmed the diagnosis of a pulmonary artery sarcoma. Local recurrence was detected in the adjacent tissues several months after the surgery. Given the potential risk of reoperation, the patient was suggested to undergo conservative treatment.

Surgery

Echocardiography

Pulmonary artery sarcoma

outflow tract

Right Ventricular

Case report

Pulmonary artery sarcoma (PAS) is a rare and lethal malignancy that primarily originates from the main pulmonary arteries or pulmonary valve, but it may also involve the right ventricular outflow tract (Burke and Virmani 1993; Hoiczyk et al. 2012).The anatomical location is the one that determines the clinical presentation, treatment, and prognosis of cardiac sarcoma (Blackmon and Reardon 2010). Masses involving the right ventricular outflow tract (RVOT) may result in obstruction but also in sudden death. Therefore, early diagnosis is essential for the long-term prognosis of the disease but also for ensuring better quality of life in patients. Due to the similar symptoms and imaging findings between PAS and pulmonary thromboembolism (PTE), and since both conditions can develop in some cases simultaneously, diagnosis and treatment of PAS may often be missed or delayed. Consequently, it is essential to distinguish PAS from primary cardiac tumors when the RVOT is involved, and to combine various imaging methods to facilitate differential diagnosis and exact tumor localization.

A 34-year-old female presented with the chief complaint of exertional chest tightness and chronic cough for two weeks and for more than one year, respectively. Computed tomography (CT) performed at an outside hospital led to the diagnosis of acute pulmonary embolism. After being treated with anticoagulation for four days, the patient was admitted to the respiratory department. Physical examination upon admission revealed no positive signs. Malignant lesions in the middle lobe of the right lung had been detected via CT, transbronchial lung biopsy (TBLB), and positron emission tomography-CT (PET-CT) one year before. Based on physical/imaging examinations findings and histological and immunohistochemical analysis, the patient was diagnosed with inflammatory myofibroblastic tumors with multiple metastases in the right lung by the responsible pathologist. Following treatment with anlotinib for approximately half a year, symptoms were relieved and gradually recovered, and the largest mass in the computed tomography (CT) images was reduced significantly. The patient discontinued the medication just one month prior to admission. However, symptoms of chest tightness and shortness of breath reappeared approximately two weeks before. Pulmonary CT re-examination at an outside hospital indicated that the distal branch of the right upper pulmonary artery was poorly visualized, and the surrounding soft tissue, which initially appeared to be an opaque shadow, was considered a metastasis. Nodular filling defects were detected in both the pulmonary trunk and the left lower pulmonary artery. A small amount of fluid was also observed in the right thoracic cavity and pericardium.

Laboratory results on admission showed abnormal liver function (ALT:54U/L, AST:79U/L, GTT:104U/L) and an elevated plasma level of the NT-Pro BNP (1155 pg/ml). Routine laboratory examinations, including coagulation and fibrinolysis index profile, were normal. Continuous anticoagulation was used together with prophylactic liver protecting drugs. Two days after admission, the echocardiogram revealed a pedunculated mass in the right ventricular outflow tract (RVOT), which was closely related to the pulmonary valve, and protruded to the pulmonary artery during systole (Fig. 1A). Consequently, the right ventricular outflow tract obstruction was characterized by a tricuspid regurgitation gradient of 62mmHg, a peak transpulmonary valve gradient of 39.7mmHg, right ventricular dysfunction (TAPSE: 14 mm), right heart dilatation (58⋅66 mm), and right ventricular hypertrophy (5.2 mm), as well as trivial pericardial effusion (Fig. 1B, C). Computed tomography pulmonary angiogram (CTPA) performed on the same day revealed acute pulmonary embolism in the left lower pulmonary artery branch. Thrombosis or tumor thrombosis was suspected in the main pulmonary artery involving the right ventricular outflow tract (Fig. 1D). It was also apparent that multiple abnormal shadows in the middle lobe of the right lung and lymph nodes in the right hilum and posterior mediastinum were metastatic lesions. After reviewing the patient’s previous data together with CTPA from the outside hospital, PET/CT, and enhanced chest CT, we identified that the mass had been present for more than one year and showed progressive enlargement with no response to anlotinib. We inferred that the PAS may have been missed in the early stage due to its small size but also because the therapeutic focus was predominantly on pre-existing lung lesions.

These findings encouraged the physician to perform additional investigations to the pulmonary artery with magnetic resonance imaging (MRI) so as to further evaluate its relationship with the pulmonary valve and right ventricular wall, optimize tumor resection, which was located around the pulmonary valve and extended to the RVOT along with the valve (Fig. 1E), and revealed poor demarcation with the right ventricular wall. Computed tomography venography of bilateral lower extremities excluded deep vein thrombosis (DVT).

In an attempt to relieve right ventricular outflow obstruction, cardiac surgery was performed to resect the right ventricular mass under intraoperative transesophageal echocardiogram monitoring and evaluation (Fig. 1F, G). Three well-capsulated masses (approximately 3.5⋅2 cm, 1.5⋅1.0 cm, 0.5⋅0.5 cm, respectively) adhered to the bottom of the interventricular septum in the right ventricular via pedicles (Fig. 1H, I). Pathological examinations showed that the tumors consisted of spindle-shaped cells. Immunohistochemical stains showed positivity for FLI-1, SMA (partial+), CD34 (partial+), CD31 (vascular+), KI67 (40% +), and vimentin. In contrast, ERG, FVIII, S-100, SOX10, CK7, CK20, EMA, and desmin were negative. Based on the above findings, the primary diagnosis was pulmonary artery sarcoma.

After surgery, the right ventricular function (TAPSE: 15.2 mm) improved gradually following relief of the obstruction. Furthermore, echocardiography revealed that the tricuspid regurgitation gradient (49mmHg) and the peak transpulmonary gradient (21.3mmHg) were significantly reduced. However, seven weeks after discharge, the patient presented again with a tumor recurrence around the primary site, and was suggested to undergo conservative treatment. Nevertheless, a poor prognosis was expected in this case due to recurrent and infiltrative lesions.

PAS is a malignant mesenchymal tumor originating from the pulmonary trunk and pulmonary arteries intima that is partially involving the pulmonary valve and right ventricular outflow tract. Its prevalence is approximately 0.001–0.030% and has a poor prognosis if left untreated (Cervilla-Muñoz et al. 2020). Clinical presentation and imaging findings of pulmonary artery sarcomas are similar to pulmonary thrombosis (PE), leading to a high misdiagnosis rate (Bandyopadhyay et al. 2016). Indeed, PAS is usually obscured when acute or chronic pulmonary thromboembolism with a tendency for thrombosis is also present (Skiba et al; Lu and Yin; Serra et al.). A similar case reported by Xu et al. showed the retrograde extension of sarcoma to the pulmonary valve and right ventricle, which was initially misdiagnosed as PTE by CTPA but was eventually corrected by echocardiography (Xu et al. 2020). Yeung et al. outlined the differences between PAS and PE on echocardiograms, including mobility, absence of echo lucent areas, bulging rather than linear morphology, and attachment to the pulmonary valve or pulmonary artery wall (Yeung et al. 2018). According to the mobility of the masses and pedicles attached to the interventricular septum and echocardiogram findings, the masses located in the right ventricular outflow tract were diagnosed as tumors instead of thrombosis, which was consistent with the findings of Wang et al (Wang, Ren, and Yang 2016). Thus, echocardiography is a valuable imaging modality for the differential diagnosis of PAS and PTE involved in the pulmonary trunk and right ventricular.

In our case, the growth pattern of the tumor originated from the RVOT to the pulmonary valve, hence, it was essential to differentiate this tumor from cardiac tumors such as cardiac myxoma and cardiac sarcoma. The majority of cardiac angiosarcomas occur in the right atrial and are primarily non-mobile with a broad-based attachment to the endocardial surface (Kupsky et al. 2016). Al Umairi et al. reported a case of cardiac hemangioma diagnosed by CMR before surgery, and demonstrated that CMR might contribute to the differential diagnosis of cardiac tumors composed of different components, such as fibroma, rhabdomyoma, lipoma, and myxoma (Al Umairi and Sabek 2021). In this case, ultrasonographic findings on the mobility and pedicles of the masses were similar to those of cardiac myxoma, hence their nature could not be elucidated. Lung tumors with a similar histological pattern are predisposed to be multiple lesions from the tissue of origin. When masses develop in the RVOT or the pulmonary artery with numerous concurrent lesions in the lung, particular vigilance is required to confirm the possibility of a tumor. Every doubling of the time from onset to diagnosis increases the probability of death by 46% (Cervilla-Muñoz et al. 2020). In this case, it is a pity that although the tumor in the RVOT developed in the early stage, it remained unnoticed and untreated, thus leading to the expected adverse outcome. Despite the fact that the efficacy is not yet conclusive, surgical treatment offers the best opportunity for symptom relief and improved long-term outcomes (Yin et al. 2018). Thereby early detection is necessary to improve survival rates.

Cardiac sarcoma and pulmonary artery sarcoma are burdensome malignancies, yet, it is unnecessary to distinguish these two tumors absolutely due to their similar presentation and treatment options. However, a differential diagnosis of pulmonary artery sarcoma, pulmonary thromboembolism, and cardiac myxoma is very significant. Physicians and radiologists should be alert to the possibility of concurrent lesions in the main pulmonary artery or right ventricular when peripheral malignant mesenchymal tumors are observed. It is necessary to discriminate lethal lesions and perform timely intervention. Echocardiography is helpful for the early detection of tumors in the RVOT and the main pulmonary artery. Consideration of imaging findings and clinicopathological results can facilitate the differential diagnosis of pulmonary thromboembolism and cardiac tumors.

Data Availability The data that support the findings of this study will be made available on request from the Corresponding author.

Ethics Approval All procedures were approved by Scientific Ethics Committee and Review Board of the School of Pharmaceutical Sciences the 3rd Xiangya hospital affiliated with Central South University, China.

Consent to Participate This case study was conducted and reported with the consent of the patient.

Consent for Publication The authors affirm that the study does not include any participants.

Competing interests The authors declare no competing interests.

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An Unexpected Settler in the Right Ventricular Outflow Tract in Pulmonary artery sarcoma

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