A rare case of superior vena cava lipoma: its presentation from non-invasive examination

A 54-year-old man had episodes of supraventricular tachycardia and atrial flutter. From echocardiography, a mass was found at right atrium (RA). Computed tomography scan showed an elongated lesion with low density (−102 HU) arised from superior vena cava (SVC) to RA (Panel A). Magnetic resonance imaging examination confirmed a big capsulated mass that arised from SVC to RA (sized 12 × 4 × 4 cm). From steady-state free precession images, the mass was not so mobile. The mass was hyperintense at T1-weighted image (Panel B) but hypointense at fat suppression technique such as T1-spectral presaturation with inversion recovery (T1-SPIR) image (Panel C). These indicated the existence of fat-rich content in the mass. In contrary, water content in the mass was not detected as there was no hyperintense feature at T2-short Tau inversion recovery image (Panel D). The intensity of the mass was not changed during perfusion images acquisition and there was no enhancement of fibrosis at the mass. We diagnosed the mass at SVC and RA as lipoma. From surgery, a yellowish mass enclosed by a fine fibrous capsule with size of 12 × 5 × 4 cm was removed from SVC and RA (Panel E). There was a stalk that attached the mass with the distal part of right subclavian vein. Microscopic findings found mature white adipose cells with non-centrally located nuclei dominated this mass, thin fibrous septa in some parts, and a few of blood vessels (Panel F). The histologic examination confirmed the mass as lipoma.