An Unusual Epicardial Mass

Case Contribution: 
Dr. Nilay Nimbalkar DMRD, DNB
Founder-Director Precision Scan and Research Centre, Nagpur

An elderly lady presented with complaints of progressive breathlessness for a month. Chest radiograph revealed cardiomegaly.

Figure 1. 2D Echocardiography. Shows Pericardial Effusion (Blue Arrow) and a hypo to isoechoic epicardiaac lesion (Yellow Arrow). She was referred for a cardiac magnetic resonance imaging (CMR) to further characterise the abnormality.

Figure 2a & 2b – Balanced echo and Fat saturated post gadolinium T1 images are given below

What are your findings? What is the epicardial lesion that was seen on echocardiogram?

Diagnosis:

MRI findings reveal pericardial effusion along with hyperintense epicardial lesion on balanced echo images (2a).  There is complete suppression of the signal from the epicardial lesion on Fat saturated T1W images (2b). No pericardial thickening or abnormal post contrast enhancement was observed. Fat density of the epicardial lesion was also confirmed on plain CT sections (Fig 3).

Figure 2a: Still image of cine steady-state free precision CMR sequence in the short axis plane  demonstrating a large pericardial effusion (yellow arrow) and an Indian ink artefact corresponding to the visceral pericardium (blue arrow). The visceral pericardium is separated from the epicardium by a hyperintense lesion occupying the epicardial space.

Figure 2b: Fat saturated post gadolinium T1 image in the axial plane demonstrating the suppression of signal from the epicardial lesion (green arrow) . Signal intensity of epicardial lesion is similar to the subcutaneous fat confirming the diagnosis of epicardial lipomatosis.

Figure 3: Plain CT scan of the chest in the axial plane also confirms the presence of epicardial fat (blue arrow). Also, note that this epicardial fat encases the coronary vessels (yellow arrows) with no mass effect on the adjacent structures.

Pericardiocentesis revealed scattered mesothelial cells and lymphocytes. No atypical or malignant cells were seen. Therapeutic pericardial window procedure was performed. Biopsy of epicardial lesion was also performed during the surgery. Pericardial biopsy revealed nonspecific chronic inflammatory changes, which might have caused pericardial effusion. Epicardial lesion biopsy confirmed presence of adipose tissue, consistent with epicardial lipomatosis. Patient had significant relief of symptoms after pericardiocentesis and pericardial window procedure. She was advised regular follow up with echocardiography.

Discussion:

Cardiac lipomatosis is characterized by the accumulation of non-encapsulated mature adipose tissue caused by hyperplasia of lipocytes. The aetiology is unknown, but may be associated with obesity and advancing age.  Lipomatous hypertrophy of the interatrial septum is the most common fat containing lesion in heart. Characteristic sparing of fossa ovalis, helps to differentiate it from other lesions. Epicardial fat deposition is also common and it may mimic a mass on transthoracic echocardiography. Our case highlights the importance of tissue characterisation provided by CMR. These lesions may be difficult to characterise by echocardiography, hence, non-invasive imaging in the form of CMR or CT may be used to confirm diagnosis.

Final Diagnosis

  1. Chronic idiopathic pericarditis with large pericardial effusion
  2. Epicardial lipomatosis.

References:

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