Dumbbell in the heart!

Clinical History

A 67-year-old lady was being evaluated for loss of appetite and vague upper abdominal discomfort for the past 6 months. The patient had no chest symptoms.

Imaging Findings

Sections obtained through the lower chest while performing an axial contrast enhanced abdominal CT revealed a prominent lipomatous lesion within the inter-atrial septum displaying a characteristic dumbbell shape.

Discussion

Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign condition characterised by accumulation of non-encapsulated lipomatous tissue within the interatrial septum [1-7]. Lipomatous hypertrophy is actually a misnomer as microscopically the entity actually represents hyperplasia of the adipose cells. The exact aetiopathogenesis of LHIS is not well understood, nevertheless, it is encountered more frequently in obese people and female gender, and its incidence rises with increasing age [2, 5-7].

LHIS is now being increasingly recognised at cross-sectional imaging especially with MDCT and MRI. Heyer CM et al. prospectively studied 1, 292 consecutive patients who underwent MDCT of the thorax and found discovered LHIS in 2.2% of patients in their series [7]. The majority of people are incidentally detected to have LHIS on routine imaging or during cardiac surgery. The affected population is mostly asymptomatic; although LHIS has been associated with atrial arrhythmias, recurrent pericardial effusion, p-wave changes at ECG, circulatory obstruction, and sudden death [2]. Rarely, in those patients who experience intractable symptoms, surgical excision of the lesion may provide relief [4].

At imaging, LHIS characteristically manifests as a dumbbell-shaped fatty mass along the interatrial septum [1, 2, 7]. The lipomatous septal thickening typically spares the fossa ovalis consequently taking on a classical dumbbell or hourglass configuration [1-3, 5-7]. It tends to be greater than 2 cm in thickens [3, 5, 7]. LHIS is typically confined to the interatrial septum without any intercavitary or extracardiac component [1, 2]. It may surround adjacent vascular structures but does not invade them [2]. In contrast to lipoma (which is an encapsulated sharply-marginated tumour), LHIS shows non-encapsulated masses of fatty tissue. LHIS typically exhibits signal-intensity / attenuation value similar to that of subcutaneous fat; thus, easily ruling out the possibility of other cardiac neoplasms such as myxoma, rhabdomyoma, fibroma, fibroelastoma, and mesothelioma. Prior knowledge of the specific location, characteristic shape, and imaging characteristics of LHIS can facilitate the radiologist to effortlessly reach the correct diagnosis and avert mislabelling it as a more ominous lesion.

Differential Diagnosis List

Final Diagnosis

Lipomatous hypertrophy of the interatrial septum

URL:	https://eurorad.org/case/9532
DOI:	10.1594/EURORAD/CASE.9532
ISSN:	1563-4086