S5383 Right Atrial Invasion by Hepatocellular Carcinoma Tumor Thrombus: A Rare Premortem Diagnosis

Introduction: Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide and a major cause of cancer-related death. Cardiac metastases, although rare, are reported in 2.3%–18.3% of cases, mainly from lung, breast, melanoma, mesothelioma, and hematologic cancers. Premortem diagnosis of right atrial (RA) involvement is rare. We present a case of HCC with tumor thrombus (TT) extending into the RA diagnosed before death. Case Description/Methods: An 88-year-old woman with lung cancer (post-radiation), chronic obstructive pulmonary disease, diabetes mellitus, atrial fibrillation, prior embolism, peripheral vascular disease, hyperthyroidism, and a 75-pack-year smoking history was admitted after a near-syncope fall and 2 weeks of right upper quadrant pain and exertional dyspnea. Exam showed abdominal distension, hepatomegaly, elevated jugular venous pressure, and leg edema. ECG revealed atrial fibrillation with a rapid ventricular rate. Transthoracic echocardiography (TTE) showed biatrial enlargement and a dilated right ventricle with preserved left ventricular function. Labs showed aspartate aminotransferase (AST) 139 U/L, alanine aminotransferase (ALT) 31 U/L, alkaline phosphatase (ALP) 387 U/L, bilirubin 3.8 mg/dL, albumin 2.6 g/dL, international normalized ratio (INR) 5.7, and PTT 107 sec. She had lactic acidosis (3.0 mmol/L), hyponatremia (123 mEq/L). Computed tomography (CT) abdomen pelvis showed a right femur fracture, cirrhosis, and HCC with TT in the portal vein, inferior vena cava (IVC), and RA. She underwent femur fixation. Postoperatively, her condition worsened, requiring intubation. She developed severe lactic acidosis (32.3 mmol/L), tumor lysis syndrome, and hyperuricemia and electrolyte imbalances. Multi-organ failure followed with anuria, AST 7,000 U/L, ALT 1,732 U/L, ALP 1,150 U/L, INR 7.7, and hyperammonemia (109 µmol/L). Tumor markers were elevated: CA 19-9 433.2 U/mL, CEA 3.7 ng/mL, AFP 157.5 ng/mL. Despite efforts, she passed away under palliative care. Discussion: HCC with right atrial involvement may present with nonspecific symptoms such as dyspnea or syncope. TTE is the first-line tool for detecting cardiac metastases, though thrombus may be missed without contrast. This case illustrates the rarity and aggressiveness of HCC with tumor thrombus in the RA, IVC, and portal vein. Surgery was not feasible due to comorbidities. Systemic therapies like sorafenib and transarterial chemoembolization may offer limited benefit, but prognosis remains poor. Early contrast-enhanced CT is critical for diagnosis. The lack of guidelines for managing HCC with right atrial invasion highlights the need for further research.