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Logo of thijTexas Heart Institute JournalSee also Cardiovascular Diseases Journal in PMCSubscribeSubmissionsTHI Journal Website
Tex Heart Inst J. 2010; 37(4): 472–475.
PMCID: PMC2929870

Monophasic Synovial Sarcoma Presenting as Mitral Valve Obstruction


We report the case of a 26-year-old man who experienced progressive left-sided chest pain and 2 episodes of near-syncope. Studies revealed a 15-cm mass in the upper left lung, a 10-cm mass in the medial base of the left lung, and a 5-cm left atrial mass that involved the left lung, infiltrated the left pulmonary vein, and prolapsed into the mitral valve, causing intermittent obstruction. The patient underwent surgical excision of the left atrial tumor. Pathologic evaluation confirmed the diagnosis of monophasic synovial sarcoma.

To our knowledge, this is only the 3rd report of left atrial invasion and resultant mitral valve obstruction from a synovial sarcoma that infiltrated the pulmonary vein. We believe that this is the 1st documented case of a metastatic left atrial synovial sarcoma in monophasic form.

Key words: Heart neoplasms/pathology/surgery, neoplasms/epidemiology, sarcoma, synovial/complications/diagnosis/genetics/pathology/radiotherapy/surgery/therapy/ultrasonography, thoracic neoplasms/surgery, tomography, X-ray computed, translocation, genetic/genetics

Soft-tissue sarcomas comprise just 1% of all cancers that are diagnosed annually in the United States.1 Synovial sarcoma, a rare soft-tissue sarcoma, typically arises from the para-articular soft tissues of the extremities and is rarely found at sites that have no apparent synovial structures.2 The aggressive nature of synovial sarcoma makes its early detection difficult, and patients usually present with symptoms of local obstruction or functional interference. Here, we report and discuss the case of a patient who experienced such symptoms.

Case Report

In January 2007, a 26-year-old man was transferred to our institution for evaluation of worsening left-sided chest pain, cough, and exertional dyspnea of 2 months' duration. He had experienced 2 episodes of near-syncope, most recently 1 day before admission. He had lost 10 pounds in the past year. His family medical history included throat and gastrointestinal cancers in his uncle and grandmother.

Auscultation revealed decreased breath sounds in the left chest with end-inspiratory crackles in the left basal area, a decreased S1, and a soft diastolic murmur in the mitral valve area. The patient's oxygenation was adequate, and there was no sign of congestive heart failure.

Chest radiography revealed mediastinal widening with obscuring of the left cardiac border, the dome of the diaphragm, and the left costophrenic angle (Fig. 1). Computed tomography (CT) showed a 15-cm-diameter mass within the upper left lung, with some coarse calcification, and a 10-cm-diameter mass in the medial base of the left lung (Fig. 2). The masses abutted the mediastinum and compressed the left pulmonary artery, with invasion through the left upper pulmonary vein. The CT scan also revealed a 5-cm mass in the left atrium (LA) that prolapsed into the mitral valve. No adenopathy or bony destruction of the ribs or spine was seen. A CT scan of the neck, abdomen, and pelvis produced unremarkable results.

figure 17FF1
Fig. 1 Chest radiograph reveals mediastinal widening with obscuring of the left cardiac border, the dome of the diaphragm, and the left costophrenic angle.
figure 17FF2
Fig. 2 Computed tomograms in cross-sectional view show A) a 15-cm mass in the left upper lung and B) a 10-cm mass in the medial left lung base.

Two-dimensional echocardiography showed a large 4.4 × 2.4-cm pedunculated mass in the LA (Fig. 3). The mass most likely infiltrated the left pulmonary vein and prolapsed into the mitral valve, causing intermittent obstruction. The mean pressure gradient across the mitral valve was 14 mmHg. Left ventricular systolic function was normal. No regional wall-motion abnormality or substantial valvular regurgitation was noted.

figure 17FF3
Fig. 3 Two-dimensional echocardiograms show a large pedunculated mass (4.4 × 2.4 cm) in the left atrium in A) parasternal long-axis and B) apical 4-chamber view.

Seminoma metastasis was ruled out after ultrasonographic examination of the scrotum. The patient underwent urgent cardiothoracic surgery for excision of the LA tumor. At surgery, a large, bluish tumor in the LA was seen to arise from the left superior pulmonary vein. The mitral valve and all other intra-atrial structures appeared to be normal. The LA mass and a black nodular-appearing abnormality from the pericardial sac were sent for pathologic analysis.

Microscopic evaluation of the 6.3 × 5.2 × 2.5-cm lobulated LA mass revealed undifferentiated monomorphic blunt spindle cells that exhibited a vague fascicular and hemangiopericytoma-like pattern. Occasional atypical mitoses were present (Fig. 4). Large areas of necrosis were present. Immunohistochemical staining was positive for cytokeratin (Fig. 5A) and vimentin (Fig. 5B) and was focally positive for E-cadherin and high-molecular-weight cytokeratin.

figure 17FF4
Fig. 4 Hematoxylin and eosin-stained light microscopic images at A) low power (orig. ×40) and B) high power (orig. ×400) show the fascicular architectural and cellular structure of monophasic synovial sarcoma.
figure 17FF5
Fig. 5 Immunohistochemical staining with A) cytokeratin and B) vimentin confirms the diagnosis of monophasic synovial sarcoma (orig. ×100).

Fluorescence in situ hybridization (FISH) DNA studies of interphase nuclei were positive for translocation t(X;18), yielding a result of nuclear in situ hybridization (5′ SYT Sep 3′ SYT×1)[99]/(SYT×2)[101]. All findings confirmed the diagnosis of monophasic synovial sarcoma in this specimen and in a fresh intrapericardial specimen.

The patient was discharged from the hospital after 10 days, with follow-up in the hematology–oncology clinic. He was started on ifosfamide chemotherapy with mesna. He tolerated this well and experienced decreased exertional dyspnea after 1.5 months. Six weeks thereafter, repeat CT of the chest showed that both masses in the left hemithorax were slightly smaller.


Synovial sarcoma is prevalent in adolescents and younger adults (age range, 15–40 yr), with a predominance in men of 2.5 to 1.3–5

Primary tumors of the heart and great blood vessels are rare and usually benign, but approximately 25% are malignant, and most of these are sarcomas. The incidence of primary cardiac sarcoma is 0.0017% to 0.19% in unselected autopsy series.6–8 The most common sarcomas are angiosarcoma (31%), rhabdomyosarcoma (21%), malignant mesothelioma (15%), and fibrosarcoma (11%).9 Metastatic cardiac tumors occur 20 to 40 times more frequently than do primary cardiac neoplasms.6,9

Benign myxoma and other sarcomas (including leiomyosarcoma, osteosarcoma, fibrosarcoma, and myxosarcoma) should be considered in the differential diagnosis of LA tumor. Typically, cardiac sarcomas occur in young males, are asymptomatic, and eventually present with variable and nonspecific clinical manifestations.6 Common clinical presentations of LA tumor are cardiac mechanical disturbances from obstructed blood flow or from the creation of mitral regurgitation that produces heart failure or pulmonary hypertension. Left atrial tumors can also cause embolic symptoms from tumor fragments or thrombi that are released into the systemic circulation. Our patient experienced episodes of near-syncope that were secondary to mitral valve obstruction.

Microscopically, the classic form of synovial sarcoma is a biphasic tumor that is composed of sharply segregated epithelial and sarcomatous components (in descriptive rather than histogenic terms). Monophasic synovial sarcoma involves only 1 of the 2 components—in most instances, the spindle-cell sarcomatous component, which is easily misdiagnosed as a fibrosarcoma, hemangiopericytoma, or other spindle-cell neoplasm. Although a variety of special stains may aid in tumor identification, definitive diagnosis rests upon the presence of translocation t(X;18) (p11.2;q11.2), which is exhibited in more than 90% of synovial sarcomas. This translocation can be identified either by means of conventional molecular cytogenetics or by FISH.10,11

The aggressive nature of synovial sarcoma makes its early detection difficult. Patients usually present with symptoms of local obstruction or functional interference,12 as did our patient. The prognosis is poor and worsens with age.12 The 5-year survival rate ranges from 25.2% to 62.5%, whereas the 10-year survival rate ranges from 11.2% to 30%.13 Because of the small number of reported occurrences, there is no consensus regarding optimal therapy. The currently recommended treatment is wide surgical resection. The most common cause of death is local recurrence (50%) even after complete macroscopic resection.14 Adjuvant therapy options are radiation and chemotherapy. Cardiac radiation reduces the local recurrence rate and prolongs survival but can lead to long-term cardiac damage.10,15 Chemotherapy is for systemic control: in randomized trials, combined ifosfamide and doxorubicin therapy has appeared to be most successful.16 Large randomized multicenter trials have shown overall increased survival rates from the use of chemotherapy.

Intravascular synovial sarcoma is an extremely rare tumor. Ours is the 3rd report of metastatic synovial sarcoma that infiltrated the pulmonary vein with extensive LA spread and caused mitral valve obstruction. The 1st reported case was that of a 27-year-old man who presented with a 4-month history of palpitations and dyspnea and was found to have metastatic LA synovial sarcoma, along with a discrete synovial sarcoma in the right calf.17 The 2nd case involved a 26-year-old man who was evaluated for lower-back pain of 6 months' duration: he was found to have a synovial sarcoma in the sacrum and the lungs, with invasion of the left atrium.18 We believe that our report is the 1st documented case of metastatic LA synovial sarcoma in monophasic form.


Address for reprints: Leigh Ann Jenkins, MD, Department of Cardiology, Texas Tech University Health Sciences Center, 3601 4th St., Lubbock, TX 79430

E-mail: ude.cshutt@snikneJ.nnahgieL


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