Left Atrial Sarcoma, a CMR Mimic of Myxoma (QF_TH_046)

Thursday, January 30, 2025

4:50 PM – 5:00 PM East Coast USA Time

Location: Blue Room PreFunction

Presenting Author(s)

MP

Maria Isabel Camara Planek, MD

Fellow Physician
Rush University Medical Center

Primary Author(s)

MP

Maria Isabel Camara Planek, MD

Fellow Physician
Rush University Medical Center

Co-Author(s)

IK

Isna Khaliq, MD

Physician
Rush University Medical Center
JT

Janki Thakker, MD

Physician
Rush University Medical Center
DS

Daniel Sabbia, RT

Physician
Rush University Medical Center
AR

Anupama Rao, MD, FACC, FSCMR

Physician, Associate Professor of Medicine
Rush University Medical Center/St. Luke's Hospital
JS

Joanne Sutter, MD

Physician
Rush University Medical Center

Description of Clinical Presentation: A 48-year-old female with a past medical history of hypertension and dyslipidemia presented with a one-month history of dyspnea on exertion and syncope. Labs revealed elevated brain natriuretic peptide and high sensitivity troponin.

Diagnostic Techniques and Their Most Important Findings:

CT Angiogram Chest with IV contrast was negative for pulmonary embolism but revealed a large left atrial mass, perivascular and subcarinal lymphadenopathy, and a lytic lesion on the right scapula. Transthoracic Echocardiogram (TTE) showed a 3.5 x 4.1 cm mass in the left atrium extending into the Mitral Valve (MV) causing diastolic flow obstruction. Transesophageal Echocardiogram (TEE) confirmed the solid, fixed left atrial mass attached to the superior lateral wall of the left atrium, causing functional moderate mitral stenosis (MS) with a gradient of 8 mm Hg at 75 beats per minute.

Cardiovascular Magnetic Resonance (CMR) imaging was obtained for further characterization of mass, revealing a lobulated soft tissue left atrial mass measuring 3.4 x 5.7 cm arising from the interatrial septum. The mass had a centrally enhancing component surrounded by a non-enhancing shell suggestive of a vascularized stalk. Diastolic flow obstruction, functional MS, and pericardial effusion were confirmed.

Due to symptoms and mass size, a shared decision was made for resection. Peri-operative course was unremarkable, and pathology confirmed high grade intimal sarcoma.

Learning Points from this Case:

The differential diagnosis from imaging findings included atrial myxoma, sarcoma, and thrombus. Left atrial location with origin in the interatrial septum and central enhancement with classic vascular stalk was consistent with myxoma. However, mass involvement of multiple cardiac chambers and heterogenous tissue signal raises suspicion for malignant tumor.

Both myxoma and sarcoma may demonstrate iso to hypo-intensity on T1 weighted imaging, hyperintensity on T2 and cine imaging, and heterogenous uptake in late gadolinium imaging. Classically, sarcoma would have variable intensity in T1 weighted imaging with hyperintensity, hyperintensity in T2 weighted imaging, increased perfusion in first pass perfusion imaging, and in the case of classic angiosarcoma, notable delayed gadolinium enhancement demonstrating a vascular mass.

Though not pursued in our case, dedicated cardiac CT may notable help differentiate between the two masses with sarcoma demonstrating heterogenous uptake specifically in the arterial phase, with decreased contrast uptake with longer delay time. Myxoma does not have these properties on cardiac CT. In our case, CT PE protocol was done.

In summary, this case demonstrates the critical characterization of sarcoma on CMR that led to prompt diagnosis and resection.