Unconventional location for a cardiac lipoma: The anterior papillary muscle

Abstract

Primary cardiac tumors are uncommon, and lipoma is the second most frequent benign type after myxoma. The treatment of choice is surgery, with the complete excision of the mass. Nevertheless, in the absence of symptoms and clinical signs the indication for surgery is less defined, and close follow up may be recommended. In the case we are going to report the patient was followed by periodical clinical and echographic examination, always reconsidering the possibility of treatment.

<Learning objective: Cardiac lipoma is a tumor with different possible locations in the cardiac tissue and with different possible clinical patterns; in the presence of a cardiac lipoma the treatment of choice is surgery. The presence of a cardiac mass suggests investigating it with a high-resolution image examination, and to strictly follow the patient over time.>

Introduction

The most frequent origin of cardiac tumors is metastatic from other primary localizations, usually lung, breast, skin, or lymphopoietic system. According to surgical and autopsy reports, the incidence of primary cardiac tumors ranges from 0.001 to 0.3%, and approximately 75% of them are benign entities [1]. Myxoma represents the most frequently diagnosed benign cardiac tumor, followed in second position by lipoma.

Lipomas are often asymptomatic, so they are discovered casually, usually on the occasion of ultrasound cardiac imaging performed for other reasons. Occasionally patients may complain of palpitation, dyspnea, or chest oppression. Up to 75% of cardiac lipomas are located in the epicardial surface of left ventricle, the right atrium, and the interventricular septum [2]. Infrequently, the accumulation of hypertrophic fat cells, also known as lipomatous hypertrophy, can be observed in the interatrial septum.

We report the case of a patient with unusual location of a cardiac mass in the context of the papillary muscle.

Case report

A 42-year-old woman in good general condition, without cardiovascular risk factors apart from type II diabetes, was referred to cardiac surgery outpatient service of our institution with the diagnosis of a left ventricular mass. The patient presented to us asymptomatic and with negative anamnesis for chest pain, palpitation, or dyspnea episodes; neither did she show evidence of recent weight loss.

Surface echocardiography performed in a routine screening investigation revealed a left ventricular oval homogeneous mass located close to the anterior papillary muscle tissue (Fig. 1). Some associated mitral regurgitation was found; the left ventricle had a normal dimension and thickness, with a preserved systolic and diastolic function. To better define the mass, chest magnetic resonance imaging (MRI) was performed, and it showed clearly a single not pedunculated mass, diameters 28 mm × 20 mm, that was located in the context of the antero-lateral papillary muscle, adjacent to muscular tissue (Fig. 2A). We observed the characteristic loss of signal intensity due to the fat component (Fig. 2A and B); no evidence of contrast-enhancement confirmed the nature of the lesion (Fig. 2B). In T1-weighted sequences, without fat suppression, the nature of the mass is well appreciable (Fig. 3).

Fig. 1.

Apical four-chamber view echocardiography showing the mass with long and short diameters. The lesion appears like a hyper-echogenic nodule, 1.2 cm × 3.3 cm measured, with regular margins and without paroxysmal movements in the cardiac cycle.

Fig. 2.

Magnetic resonance imaging. (A) Short-axis fat suppression T2-weighted. (B) Short-axis fat suppression T1-weighted sequences after gadolinium injection. The two images show how the mass is located in the context of the antero-lateral papillary muscle, adjacent to muscular tissue.

Fig. 3.

Cardiac-gated magnetic resonance scan in T1-weighted sequence showing a single, not-pedunculated mass, in the context of the antero-lateral papillary muscle, without post-contrast injection enhancement. Frontal long-axis.

Considering the small dimension of the mass, the absence of any symptoms or hemodynamic compromise, the high probability of benign character, we did not make indication for surgery, but only for a close follow-up. We recommended a follow-up chest MRI after three months.

At one and a half years from first diagnosis, the patient underwent a new MRI control that did not show any increase in dimension of the mass. The patient obviously continued the follow-up.

Discussion

The prevalence of primary cardiac tumors in autopsy series is 1 out of 2000 and that of secondary cardiac tumors is 1 out of 100 [2]. Myxomas are the most common primary tumors, followed by lipomas, and rhabdomyomas. Lipomas occur in 8.4% of cardiac tumors, they are more frequent in adults and they are represented in almost all cases by a single lesion [3].

The diagnosis of this tumor, due to its poor attitude to invasiveness, is often accidental, but in rare cases it may cause arrhythmias, hemodynamic consequences and, in more serious situations, sudden death from coronary flow obstruction or valve obstruction.

The treatment of choice is surgery, with the complete excision of the mass, and it is indicated in case of symptoms, in case of rapid change in dimensions, and obviously in case of hemodynamic instability. Less clear is the indication in the absence of symptoms.

The presence of symptoms directly correlates with the dimension of the mass and with its position. In the literature we can find few cases of not operated lipoma; anyway it is important to underline they need a close echocardiographic follow-up [4].

In the case we report, the location of the mass is unusual: lipomas of papillary muscle described in the literature were treated for the presence of chest pain or for the associated mitral valve dysfunction. Koshy et al. described a lipoma originating from the antero-lateral muscle, surgically removed also considering the history of the patient, affected by melanoma [5].

For what concerns our case, we checked whether there was any history or family history of neoplasm, and considering the absence of symptoms, the benign character of the mass with high probability and its dimensions, the surgical risk of the procedure to remove a mass adjacent to the papillary muscle, with the risk to compromise valve function, we decided not to treat it. Moreover, on the basis of the total absence of growth in dimension, we believe that the origin of the mass, although “tumoral”, can be considered benign.

Conflict of interest

All authors declare no competing interest.