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Lipomatous Hypertrophy of the Interatrial Septum
General Considerations
- Less rare than originally thought
- Benign accumulation of unencapsulated collection of brown fat in interatrial septum
- Hyperplasia more than hypertrophy of fat cells
- Associated with older age and obesity
Clinical Findings
- Asymptomatic in most
- Atrial arrhythmias
Imaging Findings
- Imaging modalities include transthoracic or transesophageal echo, CT or MRI
- The latter allow for tissue characterization and are more accurate in assessing extent of lesion
- CT
- Non-enhancing, dumbbell-shaped mass of fat density
- Confined to interatrial septum
- Spares fossa ovalis producing dumbbell shape
- Cephalad portion thicker than caudal portion of mass
- MRI
- Homogenous, bilobed high signal mass
- Associated with mediastinal lipomatosis
Differential Diagnosis
- Myxoma
- Rhabdomyoma
- Fibroma
- Lipomas
- Very rare, well-encapsulated but may be the same entity as lipomatous hypertrophy
Treatment
- Surgical resection has been performed but is usually not required
Complications
- Can cause right atrial obstruction
- Supraventricular arrhythmias
- Unexpected cardiac death
![](../../new/caseofweek/caseoftheweekpix2010 387-/cow392-1arr.jpg) ![](../../new/caseofweek/caseoftheweekpix2010 387-/cow392-2arr.jpg)
Lipomatous Hypertrophy of the Interatrial Septum. Axial, contrast-enhanced, CT scans
through the heart demonstrate a fatty mass in the interatrial septum (blue and red arrows) which has a dumbbell shape to it (blue arrow). sparing the fossa ovalis.
For more information, click on the link if you see this icon ![](../../new/graphics/blueballoonlefttrans.png)
For these same photos without the annotations, click here and here
Lipomatous Hypertrophy of the Interatrial Septum: An Overview. O'Connor, S; Recavarren, R; Nichols, L and Parwani, A. Archives of Pathology & Laboratory Medicine. March 2006
CT appearance of lipomatous hypertrophy of the interatrial septum. Meaney, J; Kazerooni, E; Jamadar D and Korobkin, M. American Journal of Roentgenology, Vol 168, 1081-108
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