An Unusual Presentation of Metastatic Soft Tissue Sarcoma to the Left Atrium and Pulmonary Veins: A Case Report and Comprehensive Literature Review

ABSTRACT

Metastatic soft tissue sarcoma (STS) is a rare and aggressive malignancy arising from connective tissues. It is characterized by its ability to metastasize to distant sites, with the lungs being the most common location. Despite advances in diagnosis and treatment, the prognosis remains poor, particularly in cases with advanced metastasis. Management often involves a multidisciplinary approach, combining surgery, radiotherapy, chemotherapy, and newer targeted therapies. This report highlights an unusual case of STS metastasizing to the left atrium (LA) and pulmonary veins, which presented with complex clinical and therapeutic challenges. We report the case of a 74‐year‐old male with a history of synovial cell sarcoma of the left elbow, initially treated with wide resection surgery and adjuvant radiotherapy. Eight months post‐treatment, bone metastasis to the ipsilateral humerus bone was detected and managed surgically. The patient later presented with sudden‐onset numbness and weakness on the left side, along with sudden‐onset aphasia, raising suspicion of neurologic or embolic complications. Diagnostic evaluation, including transthoracic echocardiogram (TEE) and chest computed tomography, revealed a large mass in the LA and pulmonary vein, consistent with metastatic sarcoma. Open‐heart surgery was performed to resect the tumor palliatively. Adjuvant chemotherapy and radiotherapy were initiated. Follow‐up demonstrated stability of the disease for up to 1 year under the treatment protocol.

A summary of the patient's history and treatment process.

Summary.

• The metastasis of the soft tissue sarcoma to the heart and pulmonary vein is very rarely reported, and it is known as a diagnosis with very poor outcomes.

• Despite surgical and medical treatments, they usually regrow and cause serious medical complications.

• The presentation of these complicated metastatic cancers might be nonspecific, such as cerebrovascular accidents.

Abbreviations

BP

Blood Pressure

CT

Computed Tomography

CVA

Cerebrovascular Accident

ECG

Electrocardiogram

ICU

Intensive Care Unit

LA

Left Atrium

MFS

Myxofibrosarcoma

PR

Pulse Rate

RR

Respiratory Rate

STS

Soft Tissue Sarcoma

T

Temperature

TTE

Transthoracic Echocardiogram

1. Introduction

Soft tissue sarcomas (STS) represent an uncommon category of cancerous tumors derived from mesenchymal tissue, comprising approximately 1% of adult cancers [1]. It was estimated that 13,500 individuals in the United States were newly diagnosed with STS in 2019 [1, 2]. STS are complex cancers with more than 100 distinct histologic and molecular subtypes, each characterized by unique clinical patterns [3, 4]. Approximately 80% of all new sarcoma cases originate from soft tissue, and the rest originate from bone. The most common presentation is an enlarging, painless mass in the extremities or trunk [3]. The prognosis for individuals with STS remains poor, with disease‐specific survival rates ranging from 50% to 70% at 5 years [4, 5].

Studies show that as many as half of high‐risk patients with advanced STS develop metastatic disease, leading to mortality [6]. The major primary malignancies associated with cardiac metastases include cancers of the lung, breast, stomach, liver, lymphoma, leukemia, and melanoma [7, 8]. Metastases of sarcomas to the heart are rare, with only a limited number of cases reported in the literature. Their clinical presentation varies based on the site and extent of cardiac involvement. While some patients remain asymptomatic, others may develop pericardial effusion, myocardial injury, or complications from embolism or obstruction. The incidence is estimated to range between 0.001% and 0.03%, making it about 20–1000 times less frequent than primary tumors [8]. Cardiac metastases in advanced cancer carry a poor prognosis, and effective treatments remain elusive. Clinical management prioritizes enhancing quality of life, alleviating symptoms, and maximizing survival duration.

This case study presents a rare case of STS with metastases to the heart.

2. Case Presentation

2.1. History and Physical Exam Findings

The patient was a 74‐year‐old man who first presented in June 2023 at Modarres Hospital of Tehran with weakness in the upper and lower extremities of the left side and global aphasia, which began 6 h before his presentation when he woke up from sleep and was drawn to the hospital. He had experienced three similar episodes recently, each showing spontaneous improvement within a few hours. He had a history of Synovial Cell Sarcoma of the left elbow and proximal forearm, diagnosed 2 years before. After the diagnosis, he underwent wide resection surgery and adjuvant radiotherapy. After 8 months, he was diagnosed with bone metastasis to the ipsilateral humerus bone. The metastasis was treated with a surgical approach (resection of the tumor and the cement and allograft replacement). The patient had undergone adjuvant radiotherapy, too, due to his metastatic sarcoma.

The patient was anxious and cachectic in her general appearance. His vital signs evaluations showed within‐range blood pressure, respiratory rate, heart rate, and temperature (BP: 125/85, RR: 18, PR: 84, T: 36.4). The cardiorespiratory exam showed no abnormal findings. The neurologic examination revealed a weakness in the left upper and lower proximal (3/5) limbs. No other abnormality could be detected in the physical exam.

2.2. Diagnostic and Therapeutic Procedures

The diagnostic approach began with an electrocardiogram (ECG), which demonstrated nonspecific abnormal findings and did not yield a conclusive diagnosis. In his Doppler sonography, the only noteworthy point was mild calcifications without significant narrowing and stricture in both carotid arteries. His initial transthoracic echocardiogram (TTE) revealed a large, semimobile, round echogenic mass with no clear attachment point in the left atrium (LA) (Figure 1). A transesophageal echocardiogram (TEE) was performed to evaluate the patient's condition further, revealing a round echogenic mass (Figure 2). This mass exhibited several hypermobile particles on its surface. The left atrial (LA) portion of the mass measured 36 × 28 mm, with part extending into the left pulmonary veins (PV), with no evidence of stenosis in the vein. The point where the mass was attached was not visible during the TEE examination. The patient has been referred to a cardiac CT for further assessment. The chest CT revealed a lobulated mass in the left lower lobe, which invaded the left inferior pulmonary vein (Figure 3). Importantly, the other chambers of the heart and valves showed no signs of particles or masses. The ejection fraction (EF) was within normal limits, and there were no indications of significant valvular dysfunction. The brain CT scan showed no remarkable finding (Figure 4). The patient was admitted to the intensive care unit (ICU) under close observation and cardiac and respiratory monitoring, receiving anticoagulants to prevent further progression of symptoms. The medical team decided to continue treatment with the LA surgical approach due to the size of the tumor and the high risk of recurrence of cardio‐and cerebrovascular complications.

FIGURE 1.

The TTE apical four‐chamber view reveals a large, round echogenic mass in the left atrium (indicated by red arrows).

FIGURE 2.

(A) Mid‐esophageal TEE at 123° with a counterclockwise maneuver shows a tumor in the left pulmonary veins: The inferior pulmonary vein (red) and the superior pulmonary vein (blue). (B) Mid‐esophageal short‐axis TEE at 46° reveals an echogenic mass (red arrow) in the left atrium (LA) with hypermobile particles on its surface (yellow arrows), indicating high embolic risk. (C) 3D TEE provides multiple views of a tumor originating from the pulmonary veins, not attached to the LA. (D) Mid‐esophageal TEE at 0° with a counterclockwise maneuver highlights tumor extension into the left pulmonary vein (purple). The interventricular septum (red arrow), closed mitral valve leaflets (yellow arrows), and the tumor (blue) are indicated.

FIGURE 3.

(A) An axial view of a chest CT scan in the mediastinal window shows a lobulated mass lesion indicated by red arrows in the left lower lobe, which invades the left inferior pulmonary vein as shown by the blue arrow. (B) The chest CT scan in the axial view of the lung window reveals a mass lesion (red arrows) in the left lower lobe that invades the left inferior pulmonary vein, indicated by the blue arrow.

FIGURE 4.

Brain computed tomography showed no remarkable abnormality.

The multidisciplinary team decided to proceed with a palliative surgical approach due to the characteristics of the mass and the high risk of cardiovascular and cerebrovascular complications. The patient underwent open‐heart surgery 3 days after admission, after stabilizing and showing improvement in his cerebrovascular accident (CVA) symptoms. A thoracotomy was performed, during which the tumor was resected from the LA and the pulmonary vein. The extracted tumor had a loose structure and was sent to the pathology laboratory for more evaluation as it consisted of four irregular brownish‐tan elastic tissue fragments TM: 4 × 3 × 1 cm (Figure 5). The immunohistopathologic evaluation showed extensive necrotic tissue admixed with severe inflammation and atypical cells with a high N/C ratio, irregular nuclei, and hyperchromatic chromatin, suggestive of metastatic undifferentiated pleomorphic sarcoma (Figure 6). All potential sources of embolism were also removed. The recovery from surgery was uneventful. The histopathological evaluation of the tumor confirmed a diagnosis of metastatic STS. The surgical and medical teams decided to proceed with adjuvant chemotherapy and radiotherapy.

FIGURE 5.

The extracted tumor had a loose structure and was sent for more evaluation in fragments.

FIGURE 6.

Histological slides at (A) low and (B) high‐power fields show extensive necrotic tissue mixed with atypical cells with a high nucleus‐to‐cytoplasm ratio, irregular nuclei, and hyperchromatic chromatin.

3. Conclusion and Follow‐Up

The patient was discharged a week after the surgery with a stable medical condition and no new complaints or symptoms. Two months after the surgery, the evaluation revealed the tumor's regrowth and no residual or recurrent cardiac tumor in follow‐up sessions, 4–6 and 12 months later.

4. Discussion

Cardiac metastases represent a critical oncological complication, leading to critical cardiac manifestations and significantly diminishing patient prognosis within a brief diagnostic interval [9]. Metastatic cardiac tumors demonstrate a substantially higher prevalence, with incidence rates estimated to be 22–132 times more frequent than primary cardiac neoplasms [10, 11, 12]. However, literature presents varying incidences regarding cardiac tumor spread, with postmortem examinations revealing metastatic cardiac involvement between 2.3% and 18.3%, with a median prevalence of approximately 7.1% across cancer patient autopsies [13, 14].

Only a few cases of metastatic heart involvement in sarcoma have been documented in the literature. The reported incidence ranges from 0.001% to 0.03% [8]. Based on available studies, the lungs are the most frequent source of extracardiac metastases to the heart, followed by the breast, stomach, liver, lymphoma, leukemia, and melanoma. STSs primarily spread to the heart via hematogenous routes [15].

Metastatic heart disease presents significant diagnostic challenges due to its variable and nonspecific clinical features, which are influenced by tumor location and burden [16]. Its manifestations often resemble other cardiac pathologies, complicating accurate diagnosis and effective management [9, 17]. To the best of our knowledge, there is currently no available data regarding cellular or molecular markers linked to cardiac metastases of sarcomas [9].

Pericardial metastasis is the most frequently affected site, occurring in approximately 60%–69% of cases. Autopsy studies reveal that epicardial and myocardial involvement rank as the second and third most frequent sites of cardiac metastases, occurring in approximately 25%–34% of cases, whereas endocardial and intracavitary involvement is infrequent, observed in only 3%–5% [18, 19, 20, 21].

Common clinical manifestations of cardiac neoplasms include the onset of valvular dysfunction, heart failure, arrhythmias, conduction issues, syncope, pulmonary embolism, and, in severe cases, sudden cardiac death; however, the condition is often asymptomatic in its initial stages [22]. Cardiac metastasis presents different symptoms based on the location involved [23, 24]. In the case of pericardial involvement, the pericardial effusion will be the most common presentation, and in severe cases, it can progress to tamponade and Beck's triad. In cases of myocardial involvement, the signs and symptoms are associated with the degree of dissemination. Still, it mostly presents with arrhythmias (AF, atrial flutter, or ventricular abnormal beats or AVN blocks) or lowered ejection fraction (congestive heart failure) [25]. Certain tumors can reach the right atrium through the inferior vena cava and create an intracavitary mass [12].

Currently, there are no standardized treatment guidelines for cardiac metastases [9]. Limited evidence suggests that surgical intervention, when feasible, is the preferred approach to mitigate life‐threatening complications. Cardiac transplantation may offer a novel treatment approach for isolated, non‐resectable cardiac involvement. Additionally, chemotherapy and radiotherapy have shown the potential to extend survival in some patients with inoperable cardiac tumors.

We reported a case of a 74‐year‐old male with synovial cell sarcoma who developed cardiac involvement 8 months post‐treatment, presenting with a metastatic mass in the LA and pulmonary vein, identified via TEE and CT.

In a 1986 review of 120 autopsy reports, Hallahan et al. found cardiac metastases in 25% of patients with STS, with metastases to the myocardium (50%), pericardium (33%), or both (17%). However, most cases were asymptomatic and diagnosed postmortem. Symptoms included congestive heart failure, conduction blocks, arrhythmias, chest pain, and, rarely, sudden death [26].

A 2010 study by Takenaka et al. of 641 STS patients identified 11 cases of cardiac metastases diagnosed during life, with a median diagnostic age of 33 years and a median time to cardiac involvement of 36 months. Leiomyosarcoma was the most common primary tumor, with metastases often affecting the left side of the heart and typically accompanied by metastases in other organs. Symptoms included dyspnea, fatigue, or absence, and imaging methods like echocardiography and CT were pivotal for diagnosis. In seven reported cases of cardiac metastases, radiotherapy improved median survival to 10.5 months, significantly longer than the 3.5 months observed in untreated patients. The average survival from diagnosis was 8 months, and no patients underwent surgery [27].

Cardiac metastases are most commonly observed in individuals with widespread metastatic disease and a significant overall tumor burden. Consequently, the primary goals of intervention should focus on symptom palliation and delaying or preventing symptom recurrence [13]. Surgical resection is generally considered for patients with favorable prognoses, technically feasible resectable tumors, or cases of intracardiac obstruction. Bulky or rapidly growing tumors may benefit from palliative radiotherapy to alleviate symptoms and prevent cardiac dysfunction. Palliative radiotherapy often demonstrates a favorable radiographic response [28, 29].

Intracardiac obstruction due to metastases may necessitate surgical intervention. However, outcomes are often poor when the ventricular function is significantly compromised. Radiotherapy and chemotherapy can also serve as valuable therapeutic options for managing certain cardiac metastases. Given the complexity of these cases, involving a multidisciplinary team is crucial for the comprehensive evaluation and management of patients with cardiac metastasis [7, 16, 29, 30].

In a 2012 retrospective study, Agaimy et al. reviewed cardiac surgeries for sarcomas at Erlangen Heart Centre (1999–2011) and identified four cases of cardiac metastases from STS. Cardiac metastases typically emerge 109.5 months after the initial cancer diagnosis. Three patients succumbed within 14 months following surgery, whereas one patient remained disease‐free for 34 months after undergoing heart transplantation [31].

Cardiac metastases should be a differential consideration in patients with STS presenting with sudden cardiac dysfunction [9]. Palliative radiotherapy or chemotherapy can provide symptomatic relief and improve overall survival. At the same time, surgical intervention may be appropriate as a palliative approach for selected cases with isolated cardiac involvement or at risk of cardiac or embolic events [26, 27]. Routine restaging CT scans in metastatic STS should include detailed cardiac evaluation to identify potential asymptomatic metastases [31].

Author Contributions

Abdulhamid Bagheri: conceptualization. Mohammad Khani: writing – original draft. Mehrdad Jafari Fesharaki: writing – original draft. Fariba Bayat: writing – review and editing. Taraneh Faghihi Langroudi: data curation. Behrang Kazeminejad: methodology, validation. Amirreza Shahmohammadi: data curation, software, writing – review and editing. Elham Farahani: conceptualization, data curation.

Disclosure

Consent to Participate: The patient provided written informed consent to participate in this clinical case report, ensuring that all personal information and medical data would be kept confidential and used solely for research purposes.

Ethics Statement

The authors have nothing to report.

Consent

The patient provided informed consent for the publication of this report, and the center's ethical policy performed the procedure.

Conflicts of Interest

The authors declare no conflicts of interest.

Bagheri A., Khani M., Fesharaki M. J., et al., “An Unusual Presentation of Metastatic Soft Tissue Sarcoma to the Left Atrium and Pulmonary Veins: A Case Report and Comprehensive Literature Review,” Clinical Case Reports 13, no. 10 (2025): e70991, 10.1002/ccr3.70991.

Data Availability Statement

The corresponding author will provide further information upon reasonable request due to confidentiality/privacy.