Atrial invasion from primary lung adenocarcinoma extension via the pulmonary vein

Intravascular extension of lung adenocarcinoma is one of the four defined routes of metastasis to the heart but is rarely described in the literature. This is a rare case of primary lung adenocarcinoma with intravenous extension to the left atrium via the pulmonary vein. A 56-year-old female presented to the hospital with chest tightness and dyspnea. Chest computed tomography revealed a right hilar mass extending through the right superior pulmonary vein into the left atrium. Transthoracic echocardiography revealed a large, partially mobile left atrial mass occupying the entire atrial cavity and affecting mitral valve closure. Endobronchial ultrasound with transbronchial biopsy of the right middle lobe of the lung histologically showed a poorly differentiated adenocarcinoma compatible with the primary lung cancer. The patient was deemed a poor surgical candidate by cardiothoracic surgery due to the extent of metastasis and was started on chemoradiation. The patient's left atrial tumor mass started shrinking in size after starting the treatment. This unique case displaying intravascular extension of lung cancer to the left atrium has rarely been described in the literature.