Rare Right Ventricular Calcified Amorphous Tumor Mimicking Malignancy: A Case Report

Introduction

Cardiac calcification amorphous tumor (CCAT) is a non-neo-plastic intracardiac mass. It was originally described in 1997 by Reynolds et al [1], as an intracavitary mass with microscopic features of calcification and amorphous fibrinous material. The most common site is the mitral annulus followed by the right atrium (RA), right ventricle, left ventricle (LV), left atrium, and the tricuspid annulus [2]. As the clinical symptoms of CCAT resemble those of malignant tumors, including obstruction- or embolism-related symptoms, CCAT is often misdiag-nosed as a malignant cardiac tumor. We report a case of a 50-year-old man with a CCAT of the right ventricle, which underwent surgical excision.

Case Report

A 50-year-old man presented to our hospital with shortness of breath; he had been experiencing shortness of breath for more than 5 years after repeated activities. The Antibodies against Extractable Nuclear Antigens (anti-ENA) antibody spectrum test came back negative. The electrocardiogram (ECG) results demonstrated a sinus rhythm, complete right bundle branch block, and T-wave alterations. Additionally, the chest computed tomography (CT) scan revealed a slightly enlarged heart with a lack of density and calcification in the right ventricle. Admission examination revealed a 3/6 diastolic rumbling murmur that could be heard in the apical area, and moderate edema of both lower extremities. Blood examination results revealed brain natriuretic peptide (BNP) of 672 pg/mL (normal values range from 0–100 pg/mL). Transthoracic echocardiography showed enlargement of the right atrium and right ventricle, secondary right ventricular outflow tract obstruction, severe tricuspid regurgitation, and a mobile high echogenic mass from the middle of the right ventricular wall (Figure 1A). Bilateral lower extremity venous ultrasound showed local lumen thrombosis of the intermuscular vein of the right calf and abnormal blood flow spectrum of the remaining lower extremity veins, indicating the possibility of right heart insufficiency. We resected the mass surgically when the patient was stable.

During the operation, the right atrium and right ventricle were significantly enlarged. There was increased pulmonary artery return, and no terminal closure of the cardiac arterial ductus was seen on exploration after incision of the right ventricle. A stone-like mass was seen from the root of the right ventricular papillary muscle to the outflow tract (about 6×2 cm), with calcification and adhesion in the root. No thrombosis or other masses were seen (Figure 1B). Because the mass was too close to the root of the papillary muscle of the tricuspid valve, the structure of the tricuspid valve would be directly affected if the mass were to be removed. Therefore, the calcified tissue could only be partially removed. The postoperative course was uneventful. Pathologic examination of the excised mass revealed a calcified amorphous tumor (CAT). This amorphous tumor was composed of fibrin wrapped in dense calcifications; inflammatory cells and malignant cells were not observed (Figure 2A, 2B). The patient experienced an uneventful recovery following the surgical procedure. Upon comparison with preoperative cardiac color Doppler echocardiography after a 3-month follow-up period, there was no further growth noted in the mass (Figure 2C, 2D).

Discussion

CCAT was first proposed in 1997 [1]. It was first considered to be calcified thrombosis, but then was considered to be a rare benign primary tumor. However, the origin and etiology of CCATs remain unclear. According to Hemptinne’s systematic report [2], a CCAT can occur in any heart cavity or valve, but is seen predominantly on the mitral valve or annulus, in the right atrium, or in the right ventricle. As with other cardiac tumors, difficulty breathing, syncope, and embolism-related symptoms are the main symptoms of the CCAT [3], but the specificity of these symptoms is very low. These symptoms of CCAT can also result from thrombi, emboli, and other cardiac tumors.

CT scans typically reveal CCATs as irregular masses with varying degrees of calcification, either partially or diffusely, that are notably prevalent in the left ventricular chamber [4]. A distinguishing feature of CCAT is lack of enhancement when imaged with contrast medium on CT scans. Furthermore, these masses are not known to exhibit fluorodeoxyglucose (FDG) up-take in positron emission tomography combined with computed tomography (PET/CT) examinations, adding to their distinct radiological characteristics [5,6].

There have so far been limited data on the pathophysiology, treatment, and prognosis of CATs, although an association between thrombosis-induced factors and CCAT has been reported [1]. A link between CAT and end-stage kidney disease is thought to be associated with calcium homeostasis mechanism function disorder [3]. The majority of CATs are seen in association with valvular heart disease, end-stage renal disease, mitral annular calcification (MAC), or diabetes mellitus [2].

These primary cardiac tumors are rare; the most common benign cardiac tumor is myxoma [7], which is easily confused with CCAT. Myxoma can occur in any heart cavity, but, when present, is always located in the left atrium, and typically arises from the foramen ovale [8]. Myxoma should be considered in the differential diagnosis of CCAT. Myxomas are neoplasms of multipo-tent mesenchymal cells in the subendocardial tissue [9], can be round or polypoid, and are often gelatinous [10]. The main distinction between myxoma and CCAT is that myxoma can enhance on late-gadolinium-enhanced images on MRI scans [11].

Conclusions

Cardiac calcified amorphous tumor is an extremely rare nonneoplastic cardiac lesion. The pathogenesis of CCAT is unclear. Diagnosing CCAT can be challenging as there is no specific clinical presentation, and it is easy to misdiagnose it as a malignant cardiac tumor. Surgical resection is the only treatment option to reduce symptoms. Excision of the CCAT serves as both definitive diagnosis and the means to prevent embolizations.