Solitary cardiac fibroma

A 62-year-old female presented with symptoms of dyspnea, fever and myalgias, probably related to coronavirus disease 2019 (COVID-19).  

Because of sudden onset of the clinical picture and a positive D-Dimer test, a CT-pulmonary angiogram (CTPA) was performed to rule out thromboembolism.

X-ray reported mild bilateral interstitial opacities, with no other obvious findings (figure 1).

CTPA revealed findings suggestive of COVID-19 pneumonia with no signs of pulmonary thromboembolism. Incidentally, a rounded, solid epicardial mass of 6 cm was found. The left margin of the mass was well-demarcated, displacing the right ventricular free wall (figure 2).

Thoracic echocardiogram showed a medium echogenicity homogeneous mass compressing right cardiac cavities, without compromising cardiac function.

For better characterization, Cardiac Magnetic Resonance (CMR) was performed (figure 3).

Cardiac MR demonstrated the right ventricle mass, showing intermediate T1 signal and markedly hypointense T2 signal, with no significant restriction on the diffusion study. After intravenous contrast administration, the lesion did not present early gadolinium enhancement, but an intense homogeneous late enhancement at 10 minutes was noted (figure 4, 5 and 6).

Finally, intraoperative biopsy was carried out, reporting cardiac fibroma as the histological nature of the examined lesion (figure 7).

Primary cardiac neoplasms are rare (100-1000 times less common than metastatic cardiac neoplasms) and include both benign and malignant histologic types [1].

Cardiac fibromas are rare, benign neoplasm of fibroblasts in the myocardium. They are the second most common primary tumours in the pediatric population following rhabdomyomas. There is increased prevalence of cardiac fibromas in Gorlin syndrome. However, only 15% of all cardiac fibromas are diagnosed in adolescents and adults[2].

Clinical manifestations vary with size and location of the tumour. Common clinical manifestations are heart failure, arrhythmias, and sudden death, being arrhythmia the leading cause of death[1].

Less frequently, cardiac fibromas may be asymptomatic, incidentally found during imaging procedures for other indications [1] such as in our case, as the tumour was found while performing a CTPA searching for thromboembolism.

The most common location is the left ventricle, followed by interventricular septum and right ventricle, as presented.

It seems that tumour size increases with physiological cardiac growth, stopping when it is complete. Spontaneous regression is rare [3].

On echocardiography, cardiac fibromas manifest as a large, noncontractile, solid mass in the ventricular wall[2].

At CT, a homogeneous mass with soft-tissue attenuation that may be either sharply marginated or infiltrative. Calcification is often seen[2].

MRI is the primary imaging technique for cardiac tumours because of its higher temporal resolution and additional tissue characterization [4]. Multiplanar T2-Weighted, T1-weighted before and after contrast administration, delayed enhancement images and fat saturation sequences are essential for correct cardiac mass depiction [5]. Cine-MRI sequences are useful to depict the non-contracting nature of these lesions.

Because of their dense, fibrous nature, cardiac fibromas have low and homogeneous signal on T2-weighted MR images, being isointense to muscle on T1-weighted images. For the same reason, little or no early enhancement after contrast administration is frequently noted [2,4]. Furthermore, intense and homogeneous late gadolinium enhancement (related to increased extravascular bed) is a key point to clarify the fibrotic nature of this lesion besides being a feature rarely seen in any other cardiac tumour [6].

Tumour biopsy is the gold standard for diagnostic confirmation. However, histology is not always a requirement for diagnosis in the presence of clinical phenotype and typical MRI findings [3].

Cardiac fibromas, while rare, have good prognosis in adults. Surgical excision usually yields satisfactory results, being less favourable in patients with large masses, severe heart failure at initial presentation, or recurrent arrhythmias [1]. In some cases, the implantation of a cardioverter-defibrillator or cardiac transplantation should be considered [5].

We should be aware of cardiac fibroma as a diagnostic possibility when facing solitary cardiac mass.