Cardiac metastases of thyroid cancer are rare. The most common metastatic route is through lymphatic or hematogenous spread to the right side of the heart. Direct invasion of metastases from other adjacent organs to the left side of the heart is even rarer. In many cases, the disease progresses asymptomatically, and symptoms appear only when it is already fatal. A 68-year-old woman underwent total thyroidectomy and right-side lymph node dissection for papillary thyroid cancer and multiple lung metastases 7 years previously. The patient was referred to our hospital due to sudden pain in the right lower extremity and motor disturbance. Computed tomography revealed acute arterial occlusion of the right lower extremity due to tumor dispersal from a left atrial invasion caused by multiple pulmonary metastases of thyroid cancer, and only emergency thrombectomy was performed. Although blood flow was restored, the patient died of respiratory failure 2 months after the procedure. Radical resection is considered difficult in cases of direct invasion of metastases from other adjacent organs because multiple metastases have often already occurred. Therefore, in the terminal stage, it might be too invasive to resect a tumor only to prevent embolism recurrence. The treatment strategy should depend on the patient's prognosis and choice.

Cardiac tumors may be primary (either benign or malignant) or secondary (malignant) and are first detected by echocardiography in most cases. The cardiologist often challenges their identification, the differential diagnosis and the best therapeutic approach. Malignant tumors have usually a poor prognosis, which may be significantly improved by appropriate and timely therapies. The echocardiographic aspects of benign and malignant cardiac tumors described in this article, along with a clinical evaluation may orient the differential diagnosis and aid in choosing the further steps useful to define the nature of the mass.