The Syncopal Sarcoma: A Rare Case of Primary Cardiac Synovial Sarcoma.

Primary cardiac synovial sarcomas are very rare, representing <1% of all primary cardiac tumors. We report the case of a 19-year-old man with syncope and dynamic obstructive shock caused by a large right-sided intracardiac tumor. (Level of Difficulty: Beginner .).

History of Presentation

A 19-year-old man presented to a community emergency department after an episode of syncope that occurred shortly after exercise. This occurred in the context of a recent transcontinental flight. His blood pressure was initially 90/54 mm Hg but improved to 105/76 mm Hg after a fluid bolus. His heart rate was 80 to 90 beats/min, and oxygen saturation was 100% without supplemental oxygen. He had a grade III holosystolic murmur best heard over the left lower sternal border. His jugular venous pulsation was not elevated, and peripheral edema was absent. Initial laboratory investigations were significant for an elevated white blood cell count of 14.1 × 109/L and an elevated D-dimer of >4,000 ng/mL. An electrocardiogram showed sinus rhythm, right axis deviation, and right bundle branch block with appropriate discordance (T-wave inversion in V1 to V3) (Figure 1).

Figure 1

The 12-Lead Electrocardiogram From the Initial Presentation

Evidence of right heart disease with right axis deviation and right bundle branch block with appropriate discordance (T-wave inversion in V1 to V3).

Learning Objectives

To consider intracardiac tumors as an etiology for obstructive shock and syncope.

To understand the diagnostic and pathologic findings of a rare primary cardiac malignancy.

To understand the role of multimodal cardiac imaging in the diagnosis and management of intracardiac masses.

An initial computed tomography angiogram showed a very large filling defect extending from the right ventricle to the bifurcation of the right and left pulmonary arteries. A transthoracic echocardiogram demonstrated a large mass attached to the tricuspid valve extending into the right ventricular outflow tract (RVOT), causing obstruction.

Past Medical History

The patient had a history of anemia and was taking oral iron supplementation.

Differential Diagnosis

The differential diagnosis for this mass included a large intracardiac and saddle pulmonary embolism, primary or secondary tumor, or infective endocarditis. Accordingly, the patient was empirically treated with a heparin infusion and broad-spectrum antibiotics while further work-up was performed. Thrombolytic therapy was considered but was deferred given his hemodynamic stability. Given the possibility for acute decompensation from the dynamic RVOT obstruction, the patient was transferred to our tertiary care center with mechanical circulatory support capabilities and to facilitate cardiac surgery consultation. On arrival to our cardiac intensive care unit, he was urgently reviewed by an interdisciplinary team including representation from cardiac surgery, cardiology, critical care, radiology, and hematology.

Investigations

CT pulmonary angiography showed a very large 8.9 × 2.4–cm filling defect extending from the right ventricle to the bifurcation of the right and left pulmonary arteries (Figures 2A and 2B). There was a small burden of segmental and subsegmental pulmonary emboli in the right lower lobe; a small right pleural effusion; and evidence of right heart strain, with a right ventricle–to–left ventricle diameter ratio of >0.9, flattening of the intraventricular septum, and enlargement of the inferior vena cava.

Figure 2

Computed Tomography Pulmonary Angiography

The mass (A) extending into the pulmonary artery and (B) occupying the right ventricle.

A transthoracic echocardiogram (Videos 1A, 1B, 1C, and 1D) showed a large, complex, multilobulated, and cystic right ventricular mass that appeared to be attached to the tricuspid annulus (Figures 3A and 3B). The mass extended into the pulmonary artery, causing significant RVOT obstruction with a peak gradient of 32 mm Hg (Figures 3C and 3D). The right ventricle was severely enlarged with severe systolic dysfunction. There was moderate tricuspid regurgitation. The right ventricular systolic pressure was estimated at 67 mm Hg. Left ventricular size and function were normal. There was septal flattening in diastole and systole, consistent with right ventricular pressure and volume overload. There was a small pericardial effusion without signs of cardiac tamponade.

Figure 3

Transthoracic Echocardiography

(A) Parasternal long-axis and (B) modified apical 4-chamber views demonstrate the mass attached to the tricuspid annulus. (C) Flow acceleration is seen through the pulmonic valve with (D) a peak pulmonary systolic gradient of 32 mm Hg.

An abdominal computed tomography scan was performed to rule out a renal mass with extension into the inferior vena cava, and findings were negative. Doppler ultrasonography findings of the lower extremities were negative for thrombus.

Cardiac magnetic resonance was performed to further characterize the mass and confirmed the presence of a right-sided soft tissue mass with mixed signal intensity, solid enhancing portions, and cystic components, thought to be consistent with a large myxoma (Figures 4A and 4B).

Figure 4

Cardiac Magnetic Resonance

The mass (A) occupying the right ventricle and (B) extending into the right ventricular outflow tract.

Management

A plan was made for urgent surgical resection of the mass; however, while in the intensive care unit, the patient had an episode of syncope with significant hypotension, which precipitated emergent resection.

The mass was approached through a standard median sternotomy with central arterial and bicaval venous cannulation. The large cystic mass was attached to the right ventricular endocardium, was entangled within the tricuspid anterior leaflet and subvalvular apparatus, and extended into the pulmonary artery. Part of the mass and tricuspid valve were resected through a right atriotomy. A longitudinal incision was made in the right ventricular free wall to resect the bulk of the mass and myocardium surrounding the attachment point (Figure 5A, Video 2). The tricuspid valve was repaired with an Edwards MC3 annuloplasty ring (Edwards Lifesciences). The patient’s postoperative course was uncomplicated.

Figure 5

Diagnostic and Molecular Pathology

(A) Gross image showing a lobulated, smooth tumor composed of 2 attached portions (6.1 × 4.5 × 2.4 cm and 4.0 × 3.5 × 1.7 cm). (B) Microscopic image showing poorly differentiated round cell morphology (hematoxylin and eosin [H&E]; original magnification: ×200). (C) Microscopic image showing spindle cell morphology (H&E; original magnification: ×400). (D) Immunohistochemistry: diffuse and strong nuclear staining for the transcriptional corepressor TLE1 (original magnification: ×200). (E) Molecular study using a break-apart fluorescence in situ hybridization probe detecting the SS18 gene arrangement (split red and green signal).

Microscopy showed a poorly differentiated malignant tumor composed of monomorphic round and spindle cells arranged in vague fascicles and solid sheets (Figures 5B and 5C). Immunohistochemistry demonstrated diffuse positivity for transducin-like enhancer of split 1 (TLE1) (Figure 5D), CD99, and CD56, with patch positivity for epithelial markers (anticytokeratin monoclonal antibodies [AE1/AE3], cytokeratin [CK7], epithelial membrane antigen [EMA]). Molecular analysis using a break-apart fluorescence in situ hybridization probe confirmed SS18 gene rearrangement that is pathognomonic for synovial sarcoma (Figure 5E).

Discussion

Syncope is common, accounting for 1% of all emergency department visits. Ventricular outflow tract obstruction is responsible for approximately 3% of syncopal presentations, most commonly caused by hypertrophic obstructive cardiomyopathy, aortic stenosis, and pulmonary embolism. Inflow or outflow tract obstruction caused by an intracardiac tumor is rare, and primary cardiac synovial sarcomas even more so. Clinical manifestations of intracardiac tumors include arrhythmia, tamponade, and obstruction-related heart failure or syncope. In their 50-patient analysis, Wang and Li reported that 10% of patients with cardiac synovial sarcoma experienced syncope, with dyspnea and chest pain being most frequent. Complete resection is ideal, and recent literature suggests that adjunctive chemotherapy may be associated with survival benefit. Overall, the literature is sparse; as such, the prognosis is unclear, although Hammami et al estimated the survival of all patients with cardiac sarcomas to be 48.1% and 10.1% at 2 and 5 years, respectively. Multimodality cardiac imaging is critical for diagnosis, management planning, staging, and prognostication of cardiac tumors.

Follow-Up

A follow-up fluorodeoxyglucose positron emission tomography scan found no residual disease. The patient returned overseas, where he received adjuvant chemotherapy with ifosfamide and doxorubicin with growth factor support. He completed 6 cycles of adjuvant chemotherapy without toxicities.

Conclusions

This case serves as a reminder to consider intracardiac masses as a potentially life-threatening etiology of syncope and highlights the importance of multimodality imaging and a multidisciplinary approach in the diagnosis and management of intracardiac masses.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.