Intracardiac Thrombi Mimicking Cardiac Metastases in a Patient With Lung Adenocarcinoma.

CASE SUMMARY: A 50-year-old man with venous thromboembolism and newly diagnosed lung adenocarcinoma developed 2 right-sided intracardiac masses that persisted despite therapeutic anticoagulation. Findings on cardiac magnetic resonance raised concern for cardiac metastases. Histopathologic examination of the excised atrial mass demonstrated organizing thrombus, and the remaining ventricular lesion resolved after 1 month of therapeutic enoxaparin. TAKE-HOME MESSAGES: Cancer-associated intracardiac thrombi may mimic metastatic disease on cardiac magnetic resonance because their fibrin-rich and inflammatory composition can produce overlapping imaging features. When imaging and clinical findings are discordant, histopathologic confirmation may be required for definitive diagnosis and management.