Cardiac lipoma accounts for 10% of the benign tumors of the heart, generally consisting of encapsulated fatty tissue with variable origin and location [1]. Although they can present with symptoms such as fatigue, dyspnea, palpitations, chest pain or discomfort, many of the diagnosed cardiac lipomas are asymptomatic and represent an incidental finding on imaging studies [2]. In rare cases, when the tumoral mass becomes very large in size, electrocardiographic abnormalities, ventricular tachycardia and even sudden death have been described, together with pronounced symptoms of left or right outflow tract obstruction [3].

A 54-year-old man with New York Heart Association (NYHA) class III dyspnea and non-productive cough presented in a medium-care hospital. Beside hypertension and obesity class 1, there were no remarkable findings on physical examination. All laboratory testing, including erythrocyte sedimentation rate, serum C-reactive protein concentration and white blood cell count were within normal limits, yet the patient had a history of previously diagnosed and treated dyslipidemia. The electrocardiogram showed normal sinus rhythm with no additional pathological findings. The chest X-ray revealed an enlargement of the cardiac silhouette and bilateral hilar abnormalities, without evidence of pleural effusion (Figure 1a).

Figure 1: Preoperative imaging studies: (A) Chest X-ray showing enlargement of the cardiac silhouette; (B) Echocardiography examination showing a echogenic large intrapericardic mass; (C, D) CT-scan showing intrapericardic mass mimicking pericardial effusion.

As further investigations were required, the patient was referred to our clinic. While standard initial testing was unremarkable, on echocardiographic examination a large intrapericardic mass was described, approximately 11 cm length, 6 cm width and 2 cm thickness, encapsulated, with moderate echogenicity and surrounding the right and left ventricle. Although suggestive for lipomatous tumor, a CT scan was performed to exclude other possible conditions with pericardial involvement. Diagnostic imaging confirmed initial suspicion of intrapericardic lipomatous tumor (Figures 1b and 1c). As the patient was symptomatic, there was a clear indication for surgical resection of the intrapericadic tumor.

Patient underwent surgery via median sternotomy without cardiopulmonary support. Median pericardiotomy revealed an intrapericardic mass enclosing the entire antero-lateral surface of the right and the left ventricles (Figure 2). By cranial displacement of the tumor connection with the infundibular region of the right ventricle was evident (Figure 3). Complete resection was achieved, followed by hemostasis and chest tube placement. Gross evaluation of the tumor described a yellow, lobulated, and homogenous mass, covered by a fine fibrous capsule, suggestive for lipoma (Figure 4a). Histopathologic examination confirmed the nature of the examined specimen as cardiac lipoma (Figure 4b). Uncomplicated evolution allowed hospital discharge on the 6^th postoperative day.

Figure 2: Intraoperative aspect: (A) In-situ encapsulated lipomatous tumor on the anterior surface of right ventricle. (B) In-situ epicardial mass with cranial displacement.

Figure 3: Intra-operative aspects: (A) Displacement of epicardial tumor revealing right ventricle infundibulum origin; (B-D) Right ventricle infundibulum aspect during and after resection of epicardial lipoma.

Figure 4: (A) Postexcision aspect of fragmented lipomatous tumor. (B) Mature adipocytes on histological examination. (H&E staining; magnification × 10).

Accounting for approximately 10-19% of cardiac and pericardiac tumors, cardiac lipoma is a benign tumor which can cause outflow obstruction, coronary or mediastinal compression manifested as mild dyspnea, chest pain, or discomfort, palpitations, or even suddenc cardiac death [4,5]. As with common use of diagnostic imaging, cardiac lipomas are more often an incidental finding in asymptomatic patients [6].

In our case, the NYHA III dyspneea is an uncommon finding, probably due to the big mass and the origin on the infundibulum of the right ventricle. Although a wide range of location have been described, cardiac lipoma originates from the epicardial fat tissue occupying the pericardial sac, usually from the left atrium and left ventricle [7]. The origin on the right ventricular infundibulum is very rare, to our knowledge this being the first case described so far. Occasionally it can present as an intramyocardic mass displacing myocardiac fibers, causing electrical abnormalities and arrythmias. Thypically with a slow grow rate, large tumors surrounding and compressing the heart chambers may lead to hemodynamic alteration mimicking subacute or chronic pericardial effusion [2]. At this point a thorough differential diagonsis should be considered; including malignancy, metabolic abnormalities, infectious diseases, systemic inflammatory or autoimmune diseases, and imaging techniques are the best next diagnostic step.

Echocardiography usually describes a homogenous echogenic mass, playing an important role in establishing the presumptive diagnosis of cardiac lipoma. For accurate diagnosis CT scan can be helpful in differentiating low radiodensity lipomatous tumors, from other tissues, while MR imaging is able to provide a typical aspect of fat intensity comparable to that of subcutaneous tissue [7]. While CT scan is useful in determining tumor extension prior to intervention, coronary angiography should be performed to exclude their affection by the tumor [8] or by more common atherosclerotic disease that could influence the intra- and post-operative evolution [9].

Because of its slow growth rate, it is generally considered that asymptomatic patients should undergo routine echocardiographic evaluations at short intervals until symptoms or aspect changes should appear on imagistic studies [6]. In symptomatic cases, the surgical treatment include resection via median sternotomy or left/right anterior thoracotomy, although good results have been reported with less invasive methods such as video assisted thoracoscopic surgery [10].

In our case, the size and the placement of the tumor, surrounding the both ventricles, made the sternotomy mandatory, without using the cardiopulmonary bypass. As in all the previous reported cases, the postoperative course was uneventful. This case report represents an example of a rare cardiac tumor with an exceptional localization and its associated management, while current imagistic methods simplify decisions-making in the clinical practice.

The lipoma originating from the right ventricular infundibulum is a very rare situation. Although the majority of intrapericardial lipomas are usually asymptomatic, presenting as incidental findings of common diagnostic imaging, symptomatic intrapericardic masses have a surgical indication. Surgical resection is necessary not only for the alleviation of symptoms, but also for diagnostics reasons.