A rare case of a primary atrial myxoma with metaplastic ossification and its multimodal imaging features

Abstract

Introduction

Cardiac myxomas are rare, benign intracardiac tumors that arise from pluripotent mesenchymal stem cells. The vast majority of myxomas consist of mesenchymal stem cells suspended within a mucoid, gelatinous material.

Presentation of case

A 55-year-old woman presented with progressive chest pain due to a left atrial myxoma with unusual calcification. A complete resection was performed and pathology confirmed the diagnosis of myxoma with metaplastic ossification.

Discussion

This case represents the diagnostic challenges of atypical myxomas and emphasizes the importance of multimodal anatomic and functional imaging for accurate preoperative assessment.

Conclusions

This case showcases the heterogeneity of cardiac myxomas, the typical natural history, and the value of multimodal imaging in managing these rare intracardiac tumors.

Highlights

• •Cardiac myxomas are rare, benign intracardiac tumors that arise from pluripotent mesenchymal stem cells.
• •The vast majority of myxomas consist of mesenchymal stem cells suspended within a mucoid, gelatinous material.
• •Very rarely, cardiac myxomas can be calcified or ossified, posing diagnostic difficulties.

1. Introduction

Cardiac myxomas are the most prevalent primary intracardiac tumors in adults [1]. Myxomas might arise from pluripotent mesenchymal stem cells, which explains their potential for diverse cellular composition [2,3]. Most are comprised of a soft, friable material with a gelatinous consistency and smooth surface. Few myxomas exhibit areas of calcification (20 %) or ossification (8 %) [4]. Differentiating calcified or ossified cardiac myxomas from malignant metastatic cardiac tumors can be challenging due to overlapping imaging characteristics [5]. Ossified cardiac myxomas are partly difficult to assess because there are few published examples and these often do not include comprehensive cardiac imaging and histologic evaluation [6,7]. Here we present a case of a cardiac myxoma with metaplastic ossification that was successfully completely resected. This case was reported in line with the SCARE criteria [8].

2. Presentation of case

A 55-year-old woman with a history of hypertension and dyslipidemia presented with an 8-month history of progressive intermittent chest pain radiating to the left arm and lasting 5–10 s. A murmur was noted twenty years prior, but no further evaluation was pursued, and she remained asymptomatic until her current presentation. A stress test was performed which was equivocal for ischemia demonstrating mild upsloping ST depressions in leads II, III, aVF, and V3-V6 during exertion that became 1 mm horizontal ST depressions during recovery. CTA of the coronary arteries did not show any coronary artery disease, however, demonstrated a 2.5 × 2.8 × 3.1 cm rounded left atrial mass with dystrophic calcifications suspicious for a cardiac myxoma (Fig. 1A). Subsequent cardiac MRI (cMRI) further detailed a 2.9. x 2.8 cm left atrial mobile mass attached to the interatrial septum, extending to the anterior mitral valve leaflet (Fig. 1C). The mass was isointense to myocardium on T1-weighted imaging and hyperintense to myocardium on T2-weighted images with mild perfusion at the attachment to the atrial septum. Preoperative transthoracic echocardiography corroborated previous imaging and demonstrated otherwise normal cardiac function (Fig. 1B). These multimodal imaging characteristics were all consistent with a left atrial myxoma. The left atrial myxoma was resected via a trans-septal approach via sternotomy given the attachments of the mass to the interatrial septum (Fig. 1D). It was felt that resection of a small portion of the interatrial septum to include the attachment of the mass was needed for a complete resection and to prevent recurrence. The resultant interatrial septal defect was then closed primarily. The patient had no intra-operative complications and was discharged on post-operative day 3. Her symptoms of chest pain had resolved by the time of her post-operative follow up 2 months later. Final pathologic assessment of the mass was cardiac myxoma with metaplastic new bone formation.

Fig. 1.

Left atrial myxoma with metaplastic ossification (A) sagittal section of chest CT with contrast showing rounded filling defect in left atrium with dystrophic calcification (white arrow) (B) parasternal long axis view from TTE demonstrating a 2.8 × 2.9 cm mass within the left atrium above the anterior mitral leaflet (C) T1 axial MRI slice with mass originating from the interatrial septum that is isointense to the myocardium (D) yellow/white mass post-resection, with arrow indicating the point of septal attachment.

3. Discussion

Cardiac myxomas are rare, benign intracardiac tumors that arise from pluripotent mesenchymal stem cells. The vast majority of myxomas consist of mesenchymal stem cells suspended within a mucoid, gelatinous material. A small subset exhibits other characteristics such as calcification, ossification, hemorrhage, and necrosis. Ossified cardiac myxomas represent an even rarer subset, comprising <5 % of all cardiac myxomas, with fewer than 15 cases reported in the literature. The case presented here demonstrated the uncommon features of calcification on imaging and metaplastic ossification upon pathological inspection [9].

Because of their variable compositions and rarity, cardiac myxomas can pose diagnostic dilemmas. For example, previously published cases of cardiac myxomas with calcification or ossification were difficult to unambiguously diagnose by echocardiography alone because of the acoustic shadowing artifact that they elicited. In such cases, it can be difficult to differentiate among the preoperative differential diagnoses including cardiac teratoma, primary malignant tumors, malignant metastasis, or benign conditions (e.g. thrombus or vegetation) [10,11]. Key characteristics such as size, location, and degree of valvular obstruction can provide diagnostic clues, though significant overlap exists among these features. This overlap emphasizes the importance of integrating histopathological evaluation with imaging findings to establish an accurate diagnosis.

Echocardiography provides real-time dynamics, mobility, and the hemodynamics of the lesion. In contrast, CT and cMRI provide rich information about tissue characteristics and the relationship of the mass to surrounding structures, which can be important for pre-operative surgical planning. cMRI has become prominently used to help narrow the differential diagnosis is cardiac masses based on location, signal intensity, and contrast enhancement compared to normal appearing myocardium [12]. Echocardiography, CT, and cMRI are valuable imaging modalities for differentiating myxomas from malignant tumors and aiding surgical planning, though definitive diagnosis still requires a tissue sample for pathology.

The case presented here illustrates many of the principles of diagnosing and managing cardiac myxomas. First, this case is consistent with the often indolent nature of primary benign cardiac tumors, frequently arising to clinical significance only after having grown to a critical mass. Second, the cellular and molecular nature of these tumors is heterogenous and rare subsets can have features that make diagnosis difficult. In these cases, multimodal anatomic and functional imaging is useful in preoperative planning, and pathological analysis is important for final diagnosis. Finally, this case also illustrates the resolution of symptoms and complete cure after the mass is removed.

4. Conclusion

Cardiac myxomas are rare intracardiac tumors. Ossification and calcification are particularly uncommon. Ossified myxomas can pose a diagnostic challenge due to their potential to mimic secondary metastatic tumors. Myxomas typically follow an indolent course over many years, remaining asymptomatic until they reach a size that exerts a mass effect and causes hemodynamic complications. This case represents a prototypical clinical presentation of an atrial myxoma characterized by cardiopulmonary symptoms after the mass became large enough to impede cardiac function. However, calcification is unusual for myxomas which was seen on multimodal imaging in this case and indeed the final pathology revealed rarely seen metaplastic ossification.

CRediT authorship contribution statement

Satoru Osaki: Reviewing, Conceptualization, Nathan Siewert: Writing - Review and editing, Max Frenkel: Writing, reviewing and Editing, Tim Guenther: Supervision, editing.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval

The case report was deemed “non-human” research and therefore IRB approval was deemed not necessary.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

The views expressed in this material are those of the authors and do not reflect the official policy or opinion of the U.S. Government, the Department of Defense, or the Department of the Air Force.