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.