Pathological Correlation of a Cardiac Mass with Multimodality Imaging

Cardiac masses are rarely encountered in clinical practice and can lead to severe hemodynamic consequences. In addition to clinical cues, noninvasive modalities can play an important role in characterization of these masses and therefore their diagnosis and management planning. Here in this case report, we describe the use of various forms of noninvasive imaging techniques to narrow the differential diagnosis and form an operative plan for a cardiac mass later identified as a benign myxoma originating from the right ventricle on histological examination.


Introduction
Cardiac masses were traditionally identifed only during autopsy fndings; however, with the advent of widely available noninvasive imaging techniques, their diagnosis has become easier and their management a reality [1]. Advancements in these imaging modalities have led to tissue characterization and diferentiation between diferent types of pathologies prior to their histological examination. In this case report, we describe the use of multimodality imaging techniques to diferentiate between various forms of cardiac masses and how these helped in the diagnosis of the mass from the right ventricle.

Case Presentation
A female patient in her 60s with a medical history of hypertension followed up with her primary care physician for an annual physical examination. Upon evaluation, the patient denied any complaints, and a review of the system was negative for any symptoms. Cardiac auscultation revealed a regular rate and rhythm with a III/VI systolic murmur best heard at the apex. Te rest of her examination and vitals were normal. Te electrocardiogram demonstrated normal sinus rhythm with no abnormalities. A transthoracic echocardiogram (TTE) was ordered to evaluate the etiology of the systolic murmur which demonstrated moderate concentric left ventricular hypertrophy with normal cavity size and ejection fraction. A mobile, pedunculated mass was seen extending from the undersurface of the tricuspid annulus and traversing the pulmonic valve into the main pulmonary artery with mild right ventricular (RV) dilatation and hypokinesia ( Figure 1). A gated computed tomographic angiography (CTA) of the chest confrmed the RV mass with no evidence of pulmonary embolism or extra-cardiac extension ( Figure 2 and Video SF1). Patient was admitted for further evaluation and underwent a transesophageal echocardiogram (TEE), which redemonstrated a large mobile and pedunculated mass measuring 8 by 3 cm in the RV protruding into the pulmonary artery (PA) during systole. Te trans-gastric views demonstrated the attachment of the mass to the undersurface of the tricuspid annulus adjacent to the anterior tricuspid leafet via a narrow stalk measuring 1.4 cm and extending 3-4 cm into the main pulmonary artery ( Figure 3). Te mass appeared lobulated with partial enhancement on injection of commercial echo contrast, thus helping us to exclude a thrombus. On cardiac magnetic resonance imaging (CMR), the mass was hypointense on the T1 sequence, had poor uptake on frst-pass perfusion, and a heterogeneous uptake was on late gadolinium enhancement, which refective of a benign tumor like myxoma ( Figure 4 and Video SF2). Given the large size, likely benign nature, and location of the tumor, the patient underwent surgical resection of the mass. Intraoperatively, the tumor was found to be soft and friable, extending into the PA, requiring dissection of the main PA to ensure complete retrieval of the mass into the right atrium ( Figure 5). A partial tricuspid valve (TV) repair with an annuloplasty was also done. She had an uneventful course postoperatively. Patient has remained asymptomatic with no   recurrence on follow-up echocardiogram 18 months after surgery.

Pathological Findings
Pathology confrmed a smooth glistening gelatinous tan-red mass measuring 7.0 × 2.0 × 3.0 cm. Microscopically, the lesion consisted of bland cells in a basophilic matrix with a few spindle cells. No lipoblast or mitotic activity was noted. Ancillary testing using immunohistochemical stains was positive for calretinin, supporting the diagnosis of myxoma with excised margins negative for tumor ( Figure 6).

Discussion
Cardiac masses are rare and may include tumors, thrombi, vegetations, or calcifc lesions which unlike other organs can have severe hemodynamic consequences due to obstruction, embolism, electrical, or mechanical dysfunction [2]. Cardiac myxomas are the most common benign primary cardiac neoplasm seen in adults. Te majority arise from the left atrium attached to the interatrial septum with less than 5% ventricular in origin [3]. In addition to clinical cues, noninvasive cardiac imaging plays a major role in identifcation and diagnosis of cardiac masses. Basic measures such as TTE and TEE can help in the assessment of size, location, and mobility of a mass, and the added feature of 3-dimensional echocardiography can provide more accurate anatomical relationships. Te addition of contrast agents can help assess the perfusion of the mass and diferentiate between a thrombus (avascular) and a tumor (vascular) [4]. In our patient the partially contrast-enhancing nature of the heterogeneous mass helped diferentiate it as a tumor from a thrombus. TEE also helped in delineating anatomical relationships and guiding surgical access planning for retrieval of the mass.

Case Reports in Medicine
Cardiac MRI with its tissue characterization and ability to provide information about extracardiac structures can help in assessing cardiac masses. First-pass perfusion to assess vascularity (high for vascular structures) and late gadolinium enhancement (absent in thrombus) can help to diferentiate tumors from thrombus. T1 and T2 mapping along with other features can also help to diferentiate between types of tumors [4,5]. Cardiac CT can be used for more precise assessment of anatomical relations including extra-cardiac involvement but may not be required if other noninvasive measures are available. In our patient, heterogeneous late gadolinium enhancement, low frst pass perfusion, and partial enhancement on injection of commercial echo contrast helped to exclude thrombus and identify the mass as a likely benign tumor as compared to a highly vascular lesion which has high frst pass perfusion.
Tis case therefore not only describes a rare case of an incidental myxoma from the right ventricle but also shows how multimodality noninvasive imaging can be used to diferentiate masses, aid in the management of these patients, and provide excellent correlation with histological diagnosis.

Conclusion
Te imaging techniques guide in preoperative diagnosis and management of patients with an unidentifed cardiac mass. Tissue characterization through multimodality imaging may provide an excellent correlation to the pathological diagnosis of a mass.

Data Availability
Te data used to support the fndings of this study are included within the article.