DISCUSSION
Lipomatous hypertrophy of the interatrial septum (LHIAS) is usually
incidental and typically diagnosed by a transthoracic echocardiogram
(TTE) by appreciating the classic dumbbell-shaped morphology within the
interatrial septum.(5) However, an atypical appearance on TTE might
happen; therefore, multimodality imaging is required to confirm the
diagnosis of LHIAS.
LHIAS typically spares the fossa ovalis while respecting the atrial
septum boundaries.(6) TTE has low sensitivity in diagnosing LHIAS due to
limited resolution, especially when the image quality is suboptimal. A
transesophageal echocardiogram can be used to easily make the diagnosis
for LHIAS, which best appears ‘in the bicaval view’ as “globular
thickening of the interatrial septum”.
What made matters worse was that this mass was incidentally discovered
in this patient with COVID-19 pneumonia. As has been published in
several studies, accelerated thrombosis was frequently reported in
patients admitted with COVID-19. Therefore, in our case, due to severe
Covid-19 symptoms with elevated D-dimer, the mass was treated as an
intracardiac thrombus; initially, heparin and warfarin, then
subsequently with warfarin only using a target INR between 2-3.
Due to the patient’s acute respiratory distress, he was not suitable for
any intervention. Therefore, the decision was made not to proceed with
TEE to prevent further respiratory deterioration.
Typically, the borders of cardiac tumors are determined by CMR. It also
offers a superior tissue characterization. LHIAS follow the same signal
intensity of subcutaneous fat (7). Sparing the fossa ovalis and
extension of greater than 2cm in transverse diameter are unique to LHIAS
that differentiates it from lipomas. Typical findings include uniform
high signal intensity on T1 and T2 weighted images with signal
suppression on fat-saturated images.(8) They appear hyperintense also on
SSFP cine sequences, with no gadolinium contrast enhancement neither on
the first-pass perfusion nor in the delayed phase.(9) Other differential
here with fatty content would be malignant masses, which demonstrates
infiltration of anatomic structures, poor definition of borders,
inhomogeneous tissue appearance post gadolinium, and associated
pericardial or pleural effusion.(10) Thus localization, morphology, and
signal intensity tissue characterization on the CMR helps differentiate
between etiologies of tumors in the heart.