A rare papillary fibroelastoma arising from the Coumadin ridge

An 80-year-old man presented with chest pain. Electrocardiography (ECG) showed ST-segment elevation in leads I, augmented vector left (aVL), and V2, with reciprocal ST-segment depression in lead III and the other inferior leads, a pattern termed the South African flag sign (Figure 1A). Emergent coronary intervention with left cardiac catheterization and percutaneous transluminal coronary angioplasty was performed in the distal left anterior descending (LAD) artery (Figure 1B).

Figure 1.

(A) ECG showed an anterior STEMI, the ‘South African flag sign’. (B) Left cardiac catheterization showed distal left anterior descending artery acute obstruction. (C) Follow-up 2D TOE after anticoagulation therapy revealed the same echogenic large, highly mobile mass measuring 1.5 × 1.2 cm arising from a stalk in the left atrium attached to the anterior Coumadin ridge. (D) Follow-up 3D TOE after anticoagulation therapy showed the same mass in left atrium attached to the anterior Coumadin ridge. STEMI = ST-segment elevation myocardial infarction.

Following the percutaneous coronary intervention, the patient developed a pericardial effusion with tamponade, which was evaluated emergently by transthoracic echocardiogram (TTE). An incidental suspicious mass within the left atrium was detected by TTE. During the placement of pericardial window, an intraoperative transoesophageal echocardiogram (TOE) confirmed the presence of a highly mobile, echogenic mass measuring 1.5 × 1.2 cm arising from a stalk in the left atrium at the anterior Coumadin ridge. There was no evidence of infection, making infective vegetation less likely. Thrombus and other benign cardiac tumours were included in the differential diagnoses, including myxomas. It was unlikely to be Lambl’s excrescences, given its echocardiographic appearance, as Lambl’s excrescences present as very fine, thread-like strands rather than true tumours. Malignant tumours are usually highly vascularized, fast-growing, and frequently invasive in the adjacent myocardium or pericardium. As the Coumadin ridge adjacent to the left atrial appendage is a common site for thrombus, it was decided to start the patient on direct oral anticoagulant therapy. Follow-up TOE after 2 months showed persistent mass with large, highly mobile, and pedunculated mass with a characteristic ‘sea anemone’ appearance (Figure 1C and D and Videos 1 and 2).

Excision of the left atrial mass was warranted because of the risks of embolization, possible mechanical obstruction due to the size of the mass, and its potential to serve as an infectious nidus. Grossly, the specimen showed a gelatinous, pedunculated mass arising from the Coumadin ridge between the left atrial appendage and the left superior pulmonary vein, measuring about 2 × 1.5 cm (Figure 2A). Histopathology confirmed papillary fibroelastomas (PFEs) (Figure 2B).

Figure 2.

(A) Intraoperative view of papillary fibroelastoma attached to the anterior Coumadin ridge measuring about 2 × 1.5 cm. (B) Histopathology. Cardiac papillary fibroelastoma demonstrating branching, avascular papillary fronds lined by a single layer of bland endothelial cells. The individual frond cores consist of dense, hyalinized collagen surrounded by elastic fibres (haematoxylin and eosin stain, ×20).

Primary cardiac tumours are extremely rare, with an estimated incidence of 0.02% from autopsy.¹ Most of the tumours are benign, while 15% are malignant. PFEs are the second most common benign primary cardiac tumour, following cardiac myxomas.¹ PFEs typically arise from cardiac valves—particularly aortic and mitral valves—but occur less commonly at non-valvular sites (16%–20%), such as the Coumadin ridge.^2,3 PFEs are typically identified by echocardiogram, especially by TOE, which is the most sensitive imaging modality and has better spatial resolution than TTE. PFEs have a unique appearance on echocardiogram, which helps to differentiate them from other cardiac tumours: a small, highly mobile, and shimmering ‘sea anemone-like’ mass attached to a cardiac valve by a distinct, slender stalk.^2,4

In comparison, myxomas present as larger, typically gelatinous or lobular masses that characteristically arise from the fossa ovalis of the interatrial septum within the left atrium. Other diagnostic options for differentiating the primary cardiac tumours include Lambl’s excrescences, infective vegetations, thrombi, and malignant tumours. These entities can be differentiated through echocardiogram according to the characteristics, such as morphology, location, size, mobility, vascularity, growth rate, and invasion into adjacent tissues. If echocardiogram is inconclusive, multimodality imaging—such as cardiac magnetic resonance imaging (CMR) and cardiac computed tomography (CT)—can be utilized to confirm the diagnosis.⁴ CMR is helpful for differentiation of benign from malignant tumours. The benign cardiac tumours are characterized by little or no early or late gadolinium enhancement, while the malignant tumours usually have both early and late gadolinium enhancement. Besides, the late gadolinium enhancement is useful for differentiation of vascular cardiac tumours from thrombi.² Cardiac CT can show the precise attachment point and highlight the density and calcifications of tumours.^2,3

Most patients with PFEs are usually asymptomatic on presentation, although PFEs can cause stroke, transient ischaemic attack, myocardial infarction, syncope, angina, and sudden cardiac death. Approximately 30% of cases are found as incidental findings or on autopsy.^2,4

Current literature supports surgical excision for symptomatic cardiac tumours. Asymptomatic PFEs should be excised if there are high-risk features.^4,5 Despite their benign histology comprising collagen, proteoglycans, and elastic fibres, large, mobile left-sided PFEs found incidentally should be excised to prevent sudden cardiac death, systemic emboli, infective endocarditis, and transvalvular flow obstruction.^5,6 In the current case, the patient’s LAD disease could be attributed to a coronary embolism originating from the PFE or atherosclerotic plaque rupture, or a combination of both. Delineating the exact cause of the patient’s distal LAD artery obstruction between atherosclerotic plaque rupture and embolization from PFE was not feasible, as it was not clinically relevant to attempt to obtain a tissue sample from the LAD artery. The fact that the obstruction was in the distal segment and the rest of the epicardial coronaries were free of significant disease does point towards a potential embolic cause from PFE.

The South African flag sign in ECG represents acute transmural mid-anterior/anterolateral myocardial ischaemia commonly caused by an acute occlusion of the first diagonal branch of the LAD coronary artery.^7,8 Even though the first diagonal branch is the most common culprit, the pattern may also arise in case of distal LAD occlusion, which was the case in the current patient. The presence of anatomical variations, such as a long wraparound distal LAD supplying the high lateral territory, could be the reason for this pattern.⁷ Recognition of the South African flag sign as an ST-elevation myocardial infarction equivalent is critical for timely reperfusion therapy.

In conclusion, PFEs should be considered in the differential diagnosis of cardiac tumours. Early recognition and pursuing timely surgical intervention, when clinically indicated, are crucial to prevent potentially serious complications.

Author contributions

Sun Yong Lee (Conceptualization, Data curation, Resources, Validation, Visualization, Writing—original draft, Writing—review & editing [lead], Investigation [equal]), Alaa Gabi (Conceptualization, Data curation, Visualization, Writing—review & editing [equal], Formal analysis, Investigation, Methodology, Resources [lead], Supervision, Validation [supporting]), Muhammad Choudhry (Data curation, Formal analysis, Validation, Visualization, Writing—review & editing [equal], Resources, Supervision [lead]), and Manreet Basra (Conceptualization, Investigation, Methodology, Resources, Supervision, Visualization [lead], Data curation, Formal analysis, Validation, Writing—review & editing [equal])

Consent

Written informed consent was obtained from the patient. The authors affirm that the participant provided informed consent for publication of the images in Figures 1 and 2 and Videos 1 and 2.

Funding

The authors declare that no funds, grants, or other support were received during the preparation of this manuscript.

Data availability

No new data were generated or analysed in support of this research.

Lead author biography

Dr Sun Yong Lee is an internal medicine specialist and cardiovascular disease fellow whose career is defined by a commitment to clinical excellence and academic advancement. Based in Stockton, California, Dr Lee has built a professional profile centred on the intersection of complex chronic disease management and emerging cardiac diagnostic techniques.

Her academic journey began at the Ewha Womans University School of Medicine, where she earned her medical degree in 2014 with the honor of second highest academic performance. Following her foundational training, she completed a residency in Internal Medicine at San Joaquin General Hospital. Her performance and dedication during residency paved the way for her current pursuit of subspecialty expertise through a Cardiovascular Disease fellowship at St. Joseph’s Medical Center, which she is slated to complete in 2028. Dr Lee’s professional accomplishments extend beyond the bedside into the realm of clinical research. She has contributed to the medical literature through publications. This scholarly work reflects her ability to synthesize complex physiological data to improve patient outcomes and educate others. Licensed to practice in California, Dr Lee continues to bridge the gap between primary internal medicine and specialized cardiology. Her profile is that of a modern clinician-scholar, dedicated to serving the Central Valley community while staying at the forefront of cardiovascular imaging and diagnostic innovation.