Papillary fibroelastoma of the mitral valve chordae with systemic embolization

Abstract

Papillary fibroelastoma (PFE) is a rare benign tumor that most commonly involves heart valves. Cardiac PFE involving the mitral chorda is rarer. Most papillary PFE are asymptomatic; rarely, they are diagnosed because of cardiac symptoms or after an embolic event. In this case, a 70-year-old woman presented with an acute cerebral ischemic infarct. Evaluation for potential embolic source revealed a mass on the mitral chordae. The findings of cardiac magnetic resonance (CMR) tissue characterization of the mass corroborated the diagnosis of mitral valve tumor. She underwent surgical resection of this mass and histology, which confirmed a PFE.

<Learning objective: PFE are easily detected on echocardiography but are difficult to visualize with CMR. Their small size and rapid, extensive movement render adequate CMR imaging extremely difficult. This case highlights the ability of CMR to characterize the tissue characteristics and enhancement pattern which enables non-invasive assessment for the etiology of intra-cardiac masses and usually distinguishes a tumor from thrombus.>

Introduction

Papillary fibroelastomas (PFEs) are rare endocardial tumors, predominantly affecting the cardiac valves. In particular, they more commonly affect the aortic valve followed by the mitral valve [1]. A non-valvular origin was observed in approximately 16% of cases [2]. Cardiac PFE involving the mitral chorda is rarer. Transthoracic and especially transesophageal echography (TTE; TEE) is the most sensitive and reliable investigation to establish the diagnosis, exclude multiple locations, and plan the optimal surgical approach [2]. Whether a multimodality imaging approach offers significant added value compared with echocardiography alone in the diagnostic evaluation of cardiac PFE is controversial.

Case report

A 70-year-old Caucasian woman presented with diffuse weakness and expressive aphasia. Her medical history included a previous left-sided cerebral infarct with no residual deficits. She underwent a head computed tomography (CT) and brain magnetic resonance imaging (MRI), which revealed an acute ischemic infarct of the left hypothalamus, insular cortex, posterior left frontal lobe, and left caudate nucleus. Given the concern for potential embolism, a two-dimensional TTE was obtained, which revealed a 13 mm × 12 mm mass in relation to the subvalvular aspect of the posterior mitral valve apparatus (Fig. 1). To examine the characteristics of mass in detail, a TEE was performed, which showed a 14 mm × 12 mm mass on the chordae attached to the posterior mitral leaflet and a 2 mm × 3 mm echo density attached to left coronary cusp of aortic valve (Fig. 1). To further characterize this mass, imaging was obtained by cardiac magnetic resonance (CMR). It revealed a 7 mm × 8 mm round mass associated with chordae immediately below the P2 scallop of posterior mitral leaflet. This mass showed homogenous signal intensity identical to fibrous tissue on both T1 and T2 weighted sequences; fat suppression ruled out the presence of fatty lesion components. It did not enhance with first-pass perfusion. T1-weighted inversion-recovery images after intravenous administration of gadolinium diethylene triamine pentaacetate show enhancement of tumor caused by the fibroelastic tissue of the mass (Fig. 2). Absence of increased signal intensity on contrast-enhanced first-pass perfusion imaging and contrast uptake of the tumor on delayed-enhancement imaging clearly demonstrated that this mass is neither a malignant tumor, nor a thrombus. Cardiac surgery was performed, which revealed a 1 cm × 1 cm friable, gelatinous, tumor. It was associated with the posterior papillary muscle under the P2 scallop. This was excised along with one tendon which was unable to be separated from the tumor (Fig. 3). Likewise, a 2 mm mass, similar in appearance to the mitral valve tumor was noted on the left coronary cusp and was also excised. The histopathological examination confirmed the diagnosis of a PFE (Fig. 3). The patient made an uncomplicated recovery.

Fig. 1.

(A and B) 2D transthoracic echocardiography showing a mass attached to subvalvular apparatus of posterior mitral leaflet; (C) Transesophageal echocardiography (TEE) showing a mass attached to subvalvular posterior mitral valve apparatus; (D) TEE showing the echo density attached to the left coronary cusp of aortic valve.

Fig. 2.

(A and B) Three-chamber and short-axis view showing a mass, attached to subvalvular posterior mitral valve apparatus (arrow) in a steady-state free precession cine magnetic resonance image; (C and D) T1-weighted and T2-weighted turbo spin-echo sequences of the mass; (E) First-pass perfusion showing mass with no enhancement; (F) T1-weighted inversion-recovery images after intravenous administration of gadolinium diethylene triamine pentaacetate show enhancement of mass.

Fig. 3.

(A) Intraoperative photograph shows a mass adhering to the chordae attached to posterior mitral leaflet; (B) Biopsy revealed elongated and branching papillary fronds with variable amounts of avascular collagen and elastic tissue; (C) Higher power photograph of hypocellular papillary fronds with avascular collagen core surrounded by acid mucopolysaccharides and lined by hyperplastic endothelium.

Discussion

Although the prevalence of primary cardiac tumors ranges from 0.0017% to 0.28%, the PFEs are the second most common benign neoplasm of the cardiac valves after myxomas [2]. It can be a source of embolization leading to strokes, particularly in those without identifiable risk factors [1]. Kasarskis et al. [3] reported that 50% of the patients with a PFE had transient ischemic attacks or previous strokes prior to discovery of the tumor. Embolization may occur from the fragile papillary fronds or from a platelet and fibrin aggregation forming on the tumor 4, 5.

PFEs are easily detected on echocardiography, but are difficult to visualize with CMR. Their small size and rapid, extensive movement render adequate CMR imaging extremely difficult. In the present case, the high diagnostic image quality of spin-echo sequences was achieved by freezing of mitral valve motion. The mitral valve rest period was determined from a cine sequence with a high temporal resolution. Subsequently, spin-echo data acquisition was restricted to the rest period duration, thereby achieving an almost complete motion freezing of the valve and its lesion. Overall, CMR is the most important modality in differentiating tumor from thrombus and distinguishing benign from malignant cardiac masses [6]. CMR can demonstrate key indicators of malignancy including invasive behavior, tissue inhomogeneity, and higher tissue vascularity. Nearly all malignant tumors show post gadolinium enhancement and hyperperfusion character [7]. Thrombus appears as a low signal intensity filing defect in the cardiac chamber. Contrast-enhanced CMR allows differentiation between thrombus and surrounding myocardium because thrombus is avascular and hence is characterized by an absence of contrast uptake [8]. Late gadolinium enhancement studies are most useful in thrombus detection as compared to the cine studies [9]. Presence of increased signal intensity on delayed enhancement clearly differentiates PFE from thrombus. This will also help to delineate the thrombus if it is attached to PFE. This case highlights the ability of CMR to characterize the tissue characteristics, which enables non-invasive assessment for the etiology of intra-cardiac masses. However, this case reveals two important limitations of CMR: In the present case, tumor size was underestimated by CMR. This is probably related to the limitation in choosing the correct plane with the largest dimension. We were unable to detect the presence of PFE on aortic valve. Even with adequate CMR imaging, very small, mobile masses can be missed on spin-echo sequences that are needed for texture characterization.

Despite the benign nature of this tumor, it carries a substantial risk for embolic complications, particularly strokes. Once diagnosed, prompt surgical management is indicated even in the asymptomatic patient 2, 10. The surgical resection is curative, safe, and well tolerated 2, 10. Re-growth of the tumor after resection has not been reported, but it requires long-term TTE follow-up studies to monitor for recurrence.

Conclusions

This report highlights the rare chordal location of a PFE without valvular involvement. A dedicated CMR protocol for comprehensive tissue characterization is indispensable in identifying soft tissue masses. Prompt surgical resection with preservation of valvular integrity is recommended in most cases.

Contribution

All authors had access to the data and played a role in writing the manuscript.

Funding sources

None.

Conflict of interest

The authors declare no conflict of interest.