We present an 83-year-old White non-smoker woman (1.70 m, 67 kg, BMI 23) with a history of systemic arterial hypertension, diabetes mellitus type II, and a positive family history of sudden cardiac death "SCD." Her past medical history also included a hysterectomy for endometrial adenocarcinoma 14 years ago. She underwent a cardiological evaluation due to dyspnea under normal effort, which occurred in the last 2 weeks, and new onset of voice hoarseness. She denied any chest pain, fever, abdominal pain, nausea, or weight loss. The patient was normotensive during the physical examination, with a non-rhythmic heartbeat and normophonetic heart sounds, without any exciting heart murmurs. There were no signs of heart failure and no focal neurological deficit. ECG shows a new onset of atrial fibrillation. The chest CT scan showed a large left atrial mass with a tumor plug extending into the left inferior pulmonary vein, which was new in comparison to the computerized tomography scan from 2016 "5 years ago." She underwent trans-esophageal echocardiography that showed a large mass in the left atrium approximately 5 x 4 x 3.8 cm, blocking a significant portion of the left atrium ( Fig. 1 ), a contrast medium examination with SonoVue was utilized, and the color-Doppler suspected the presence of small vessels within the mass. 
 Cardiac magnetic resonance imaging "CMRI" using native as well as contrast medium enhanced sequences showed 55 x 40 x 48 mm rounded pedunculated mass in the left atrium ( Fig. 2 ), with tumor plug in the left inferior pulmonary vein, left ventricular ejection fraction, and heart dimensions were normal ( Fig. 3 ). The patient's complaint of dysphonia raised our suspicion for malignancy; for that reason, we performed a computerized tomography scan to screen for metastasis, which turned out to be unremarkable. 
The cardiac catheterization showed normal coronary arteries and preserved the left ventricle's contractility.
 The patient underwent surgical excision of the left atrial mass using cardiopulmonary bypass "CPB" ( Fig. 4 ). After median sternotomy, she was heparinized with checking of activated clotting time. Aortic-bicaval cannulation was installed, and CPB was established for 80 minutes. An aortic cross-clamp was applied for 48 minutes; the heart was arrested with an antegrade infusion of normothermic blood cardioplegic solution in the aortic root. After that, a left atriotomy was performed, revealing a large mobile vascularized tumor (5 cm x 6 cm) with pedicled origin in the left inferior pulmonary vein. The tumor was then resected ( Fig. 5 ). Special care was taken to minimize the risk of embolic complications to prevent its fragmentation. The left atrium was then closed in layers, and the root was vented. The heart was de-aired, and the aortic cross-clamp was removed. 
The weaning off cardiopulmonary bypass was routinely performed after the spontaneous return of the heartbeats. Protamine decannulation was done, and hemostasis was secured. The chest was closed in layers. The patient tolerated all the following procedures well and was monitored in an intensive care unit for 24 hours and shifted to the surgical ward later for further postoperative care, which was uneventful.
 Gross pathological examination of the resected mass revealed a partly smooth-surfaced tumor, measuring 6.0 x 5.2 x 4.5 cm with focal hemorrhages, foci of necrosis, and cystic degeneration on the cut surface. Histological examination revealed myxoid undifferentiated pleomorphic malignancy with variable myxoid areas, high cellularity with brisk mitotic activity in excess of 30 mitoses in 10 high power fields, and scattered immunoreactivity with MDM2 and CDK4 ( Fig. 6 ). These findings are consistent with myxoid undifferentiated pleomorphic sarcoma (Grade 3 according to FNCLCC). 
The patient denied any aggressive adjuvant therapy because of her advanced age. The tumor board decision was cardiac and chest CT in 3 months, and the patient was then discharged free of symptoms.