Abstract
Background
Primary pericardial malignancies are rare, and myxoid tumors may mimic hemorrhagic pericardial effusions on imaging, leading to diagnostic delay.
Case Summary
A 56-year-old man presented with pleuritic chest pain and was diagnosed with acute pericarditis and a presumed traumatic hemorrhagic pericardial effusion. Despite anti-inflammatory therapy and pericardiocentesis yielding bloody, lymphocyte-predominant fluid with negative cytology, he experienced rapid clinical deterioration. Repeat imaging revealed an encasing pericardial mass causing severe left atrial compression and functional mitral stenosis. Emergent surgical exploration identified a large solid pericardial tumor. Histopathology confirmed primary myxoid pleomorphic liposarcoma. The patient underwent surgical resection followed by adjuvant chemotherapy and radiotherapy.
Discussion
This case highlights the myxoid tumor's masquerade as a hemorrhagic effusion, the limitations of pericardial fluid cytology for sarcoma, and the hemodynamic consequences of external cardiac compression.
Take-Home Message
Persistent or recurrent bloody pericardial effusions with atypical imaging features warrant suspicion for malignancy despite negative cytology.
Key words: external cardiac compression, functional mitral stenosis, hemorrhagic pericardial effusion, multimodality cardiac imaging, myxoid pleomorphic liposarcoma, pericardial tumor
Visual Summary
History of Presentation
A 56-year-old male long-distance truck driver presented with severe, compressive midsternal chest pain of 4 hours' duration. The pain was pleuritic and positional, worsening with deep inspiration and certain positions and improving when he sat upright. He denied lower limb swelling, cough, chills, or sore throat. He reported a distinct episode of blunt chest trauma 1 month earlier when a malfunctioning truck door struck his chest.
On initial presentation, his vital signs were stable (blood pressure: 102/73 mm Hg, pulse: 89 beats/min). Electrocardiography demonstrated diffuse ST-segment changes consistent with acute pericarditis (Figure 1). Transthoracic echocardiography (TTE) revealed a moderate to large circumferential pericardial effusion without tamponade physiology. He was discharged on colchicine 0.6 mg once daily for 3 months, with a prednisone taper starting at 30 mg daily and an ibuprofen taper starting at 600 mg three times daily.
Figure 1.
Electrocardiogram at Initial Presentation
Standard 12-lead electrocardiogram demonstrating normal sinus rhythm with a rightward QRS axis and diffuse, concave ST-segment elevation and PR-segment depression.
The patient returned 1 month later with persistent symptoms. Repeat TTE demonstrated a large, loculated pericardial effusion adjacent to the left ventricle, which was confirmed by chest computed tomography (CT). Pericardiocentesis was performed, draining 300 mL of grossly bloody fluid. Pericardial fluid was a bloody exudate (red blood cells: 594,000/μL, protein: 4.8 g/dL, albumin: 3.2 g/dL) with a lymphocyte-predominant differential (73% lymphocytes), normal glucose, and low triglycerides. Cytology was negative for malignant cells, flow cytometry showed no evidence of a lymphoproliferative disorder, and bacterial, fungal, and mycobacterial cultures showed no growth. The fluid profile was consistent with a bloody, lymphocyte-predominant exudate with negative cytology and cultures. The collection was interpreted as a likely clot or hemopericardium related to prior trauma. He was advised to follow up in the pericardial clinic.
Six weeks later, he re-presented with new hemoptysis, flank pain, and tachycardia (110-120 beats/min). Laboratory evaluation revealed markedly elevated inflammatory markers, including C-reactive protein (2.3 mg/dL) and erythrocyte sedimentation rate (60 mm/h), as well as N-terminal pro–B-type natriuretic protein (2,876 pg/mL).
Past Medical History
The patient was a former smoker with no other significant past medical or surgical history. He was not on chronic medications and had no known history of malignancy, prior pericardial disease, or connective tissue disorders.
Differential Diagnosis
The classic pleuritic and positional chest pain, diffuse ST-segment changes, and a new moderate-to-large pericardial effusion were most consistent with acute pericarditis. The recent blunt chest trauma raised concern for traumatic pericarditis or traumatic hemopericardium. Life-threatening causes of chest pain, including pulmonary embolism, acute coronary syndrome, and aortic dissection, were also considered.
After pericardiocentesis, the fluid profile further refined the differential. The effusion was a bloody, lymphocyte-predominant exudate, sterile on culture and nonchylous. A lymphocytic pericardial effusion raises concern for tuberculous or viral pericarditis, malignancy, autoimmune pericarditis, postcardiac injury syndrome, and idiopathic pericarditis, while a bloody effusion suggests malignancy, trauma, aortic dissection, tuberculosis, post–myocardial infarction syndrome, uremia, coagulopathy, or infective endocarditis.
In this patient, the plausible traumatic mechanism, absence of constitutional symptoms, and negative cytology and flow cytometry made traumatic hemopericardium with organized clot the favored working diagnosis, although malignancy could not be definitively excluded.
Investigations
Repeat TTE revealed a dense posterior pericardial collection causing severe external compression of the left atrium, resulting in “functional mitral stenosis” (Videos 1A and 1B). Doppler interrogation demonstrated elevated transmitral gradients across an anatomically normal mitral valve, consistent with obstruction from extrinsic compression rather than intrinsic valvular disease (Videos 2A to 2C). CT pulmonary angiography demonstrated a small right upper lobe pulmonary embolism and a large pericardial opacity encasing the heart (Figures 2A to 2C). The mass effect compressed the superior vena cava (SVC) and pulmonary veins, with secondary pulmonary edema. The rapid evolution from a presumed loculated effusion to an encasing pericardial mass with chamber and venous compression raised significant concern for an underlying pericardial malignancy.
Figure 2.
Computed Tomography of Pericardial Mass Before and After Surgical Resection
(A to C) Contrast-enhanced computed tomography of the chest demonstrating a large pericardial mass abutting and compressing the left atrium, pulmonary veins, superior vena cava, and adjacent the great vessels (arrows). (D to F) Computed tomography after surgical resection showing complete removal of the pericardial mass with resolution of cardiac chamber to vascular compression.
Management
Given the rapid clinical progression, new hemodynamic compromise, functional mitral stenosis from left atrial compression, SVC syndrome, and imaging evidence of an encasing pericardial process, the patient was transferred to the Cleveland Clinic for higher-level care. Emergent surgical exploration was pursued.
He underwent median sternotomy. Intraoperatively, the pericardial space was found to be occupied not by loculated fluid but by a large, organized solid mass. An anterior pericardiectomy was performed with en bloc extraction of the tumor, which measured 20 × 11.5 × 2.2 cm. Postresection TTE demonstrated relief of left atrial compression and normalization of transmitral flow (Videos 1C and 1D). CT imaging after surgical resection confirmed complete removal of the pericardial mass, with resolution of vascular compression (Figures 2D to 2F). Histopathology demonstrated a variably cellular myxoid spindle cell neoplasm featuring pleomorphic lipoblasts within an abundant myxoid stroma (Figure 3). Subsequent molecular analysis revealed negative MDM2 amplification and absent DDIT3 rearrangement, ruling out dedifferentiated and myxoid liposarcomas. Finally, chromosomal microarray identified widespread genome-wide loss of heterozygosity. These findings collectively established the final diagnosis of myxoid pleomorphic liposarcoma of the pericardium.
Figure 3.
Histopathologic Features of Primary Pericardial Myxoid Pleomorphic Liposarcoma
(A) Aggregates of multivacuolated pleomorphic lipoblasts and arborizing vasculature in the background (400× magnification). (B) Arborizing vasculature and mucin pools with scattered pleomorphic lipoblasts (200× magnification).
Outcome and Follow-Up
Postoperatively, the patient's hemodynamics normalized, with resolution of functional mitral stenosis and symptoms related to external cardiac compression. He subsequently underwent systemic chemotherapy with doxorubicin and ifosfamide and adjuvant radiation therapy (70 Gy in 35 fractions), followed by close surveillance. Six months after completing therapy, Signatera testing (Natera) was positive; biopsy confirmed recurrent sarcoma in the mediastinum, adjacent to the diaphragm, and outside prior radiation fields. A repeat positron emission tomography scan is planned to evaluate for additional sites of disease, and the patient is scheduled for multidisciplinary assessment with thoracic surgery and radiation oncology for consideration of surgical and radiation management.
Discussion
Primary cardiac and pericardial tumors are rare, with an incidence of 0.001% to 0.03% in autopsy series, whereas metastatic pericardial involvement is far more common.1 Among primary malignant tumors, sarcomas predominate, and primary pericardial liposarcomas are exceptionally rare.1 This case highlights 3 key diagnostic challenges associated with the “masquerade” effect of myxoid tumors: imaging appearance, limitations of cytology, and the hemodynamic consequences of external compression.
Myxoid tumors mimicking pericardial effusion
The most deceptive aspect of this case was the tumor's imaging appearance. Myxoid liposarcomas are characterized by an abundant myxoid stroma with high water content, which can render them hypoechoic or anechoic on echocardiography and exhibit low attenuation on CT scans.2,3 As a result, they can closely resemble simple or complex pericardial effusions. In this patient, the lesion initially appeared as a circumferential effusion and later as a large, loculated posterior collection. The drainage of 300 mL of bloody fluid, interpreted as traumatic hemopericardium or organized clot, further reinforced this impression and delayed recognition of a solid mass.
Limitations of pericardial fluid cytology for sarcoma
This case also illustrates the pitfall of relying on pericardial fluid cytology to exclude malignancy. Unlike carcinomas, which often shed cells into serous cavities, sarcomas are composed of cohesive mesenchymal cells that exfoliate poorly.4 Consequently, cytology may be negative even in the setting of a sizable pericardial sarcoma.5 Here, the bloody effusion with negative cytology and flow cytometry was falsely reassuring. A recurrent or persistent bloody effusion, especially with atypical imaging features, should prompt continued evaluation for malignancy despite negative cytology.
Hemodynamic consequences of external cardiac compression
As the tumor enlarged, it encased the heart and compressed adjacent structures. Severe external left atrial compression resulted in functional mitral stenosis, characterized by elevated transmitral gradients across an anatomically normal valve. This led to pulmonary venous hypertension, providing a mechanistic explanation for the patient's hemoptysis and pulmonary edema. Compression of the SVC and pulmonary veins on CT, in combination with these hemodynamic findings, is characteristic of a solid pericardial mass rather than a simple effusion and should trigger urgent reassessment of the initial diagnosis.6
Role of multimodality imaging
Multimodality imaging is crucial in differentiating complex pericardial effusions from pericardial tumors.6,7 TTE is the first-line tool for detecting effusions and assessing hemodynamics, but it has limited ability to characterize tissue.6 Cardiac CT and cardiac magnetic resonance (CMR) provide superior anatomical detail and tissue characterization.6,7 On CT, liposarcomas may exhibit regions of fat attenuation; however, myxoid variants can have attenuation values similar to those of water, further complicating the diagnostic challenge.8 CMR is the gold standard for characterizing pericardial masses, with T1- and T2-weighted imaging, fat suppression, and gadolinium enhancement enabling the distinction among fat, fluid, myxoid matrix, and solid tumor components.9 In this patient, the rapid interval growth and encasing behavior of the pericardial opacity on follow-up CT were key red flags. Even in the absence of CMR, these features, combined with functional mitral stenosis and SVC compression, appropriately prompted emergent surgical exploration.
Management of primary pericardial liposarcoma
Management of primary pericardial liposarcoma centers on surgical resection, aiming for complete tumor removal.10 This is often technically challenging, given the proximity to vital cardiac structures and the potential for extensive involvement of the pericardium and epicardial surface.8 Adjuvant radiotherapy and chemotherapy, typically doxorubicin/ifosfamide-based regimens, are frequently employed because of the high risk of recurrence and overall poor prognosis associated with sarcomas.10 In this case, the patient underwent anterior pericardiectomy with en bloc tumor resection followed by aggressive adjuvant radiation and systemic chemotherapy.
Funding Support and Author Disclosures
Dr Klein has received research grants from Kiniksa Pharmaceuticals, Ventyx, and Cardiol Therapeutics; serves on the Advisory Boards of Kiniksa Pharmaceuticals, Cardiol Therapeutics, Ventyx, and Zydus Pharmaceuticals. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Take-Home Messages
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Myxoid pericardial sarcomas can closely mimic complex or hemorrhagic pericardial effusions on imaging and may yield falsely negative cytology, leading to diagnostic delay.
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Persistent or recurrent bloody pericardial effusion with atypical imaging features or extrinsic chamber compression should prompt urgent multimodality imaging and consideration of surgical exploration for underlying malignancy.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
Visual Summary.
| Time Point | Clinical Events |
|---|---|
| Day 1 | A 56-year-old man presented with 4 hours of pleuritic chest pain and a history of blunt chest trauma 1 month prior. ECG showed acute pericarditis; TTE revealed a moderate to large circumferential pericardial effusion. He was discharged on triple therapy: colchicine, prednisone taper, and ibuprofen taper. |
| Month 1 | Patient returned with persistent symptoms. TTE and CT demonstrated a large, loculated pericardial effusion adjacent to the left ventricle. Pericardiocentesis performed (300 mL of bloody exudate). Cytology, flow cytometry, and cultures were negative. Interpretation was likely traumatic hemopericardium. |
| Month 3 | Re-presented with new hemoptysis, flank pain, and tachycardia. Elevated NT-proBNP and inflammatory markers. Imaging revealed a dense posterior pericardial mass causing external compression of the left atrium (functional mitral stenosis), SVC syndrome, and pulmonary embolism. Emergent median sternotomy performed with en bloc extraction of a solid mass. Histopathology and molecular analysis established the diagnosis of myxoid pleomorphic liposarcoma. |
| Months 3-10 | Patient completed systemic chemotherapy (doxorubicin and ifosfamide) followed by adjuvant radiation therapy (70 Gy). |
| Month 17 | Routine 6-month post-therapy surveillance. Signatera testing was positive; biopsy confirmed recurrent sarcoma in the mediastinum. Scheduled for repeat PET scan and multidisciplinary surgical/radiation oncology assessment for recurrent disease management. |
Appendix
Transthoracic Echocardiography Demonstrating Pericardial Mass and Postresection Findings
Transthoracic echocardiography in the (A) parasternal long-axis and (B) apical 4-chamber views demonstrate a large pericardial mass causing severe compression of the left atrium. (C and D) Postoperative echocardiographic clips after surgical resection demonstrate relief of left atrial compression and restoration of normal cardiac chamber geometry.
Doppler Echocardiography Demonstrating Functional Mitral Stenosis
(A and B) Parasternal long-axis and apical 4-chamber views demonstrating flow acceleration across the mitral valve on color Doppler imaging due to extrinsic left atrial compression. (C) Continuous-wave Doppler interrogation demonstrating a mean transmitral gradient of 5 mm Hg at a heart rate of 113 beats/min, consistent with functional mitral stenosis.
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Associated Data
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Supplementary Materials
Transthoracic Echocardiography Demonstrating Pericardial Mass and Postresection Findings
Transthoracic echocardiography in the (A) parasternal long-axis and (B) apical 4-chamber views demonstrate a large pericardial mass causing severe compression of the left atrium. (C and D) Postoperative echocardiographic clips after surgical resection demonstrate relief of left atrial compression and restoration of normal cardiac chamber geometry.
Doppler Echocardiography Demonstrating Functional Mitral Stenosis
(A and B) Parasternal long-axis and apical 4-chamber views demonstrating flow acceleration across the mitral valve on color Doppler imaging due to extrinsic left atrial compression. (C) Continuous-wave Doppler interrogation demonstrating a mean transmitral gradient of 5 mm Hg at a heart rate of 113 beats/min, consistent with functional mitral stenosis.