INTRODUCTION: Cardiac tumors are rare. Metastatic deposits are more common than primary cardiac tumors. Moreover, primary mediastinal neoplasias are infrequent, corresponding to less than 10% of all thoracic neoplasias. We report, to our knowledge, the first case of an invasive thymoma invading the epicardial vessels and myocardial tissue causing acute vessel occlusion and ST-segment elevation myocardial infarction (STEMI.).
CASE PRESENTATION: A 39 year old African American male with a history of an unresected thymoma presented to our institution with a four week history of progressive dyspnea and chest pain. Physical examination revealed a blood pressure of 128/80 mmHg, bilateral rhonchi and wheezing, with occasional rales at the bases. There were no other abnormal findings on cardiac or other systemic examinations. The electrocardiogram showed ST-segment elevation in the antero-lateral leads. Emergent coronary angiography revealed a vascular structure completely occluding the left anterior descending artery. Coronary intervention was not attempted. The patient was placed on Intra-aortic balloon counter-pulsation and referred for surgical evaluation. Further imaging using computed tomography showed the large mass with scattered calcifications completely occluding the left middle mediastinum with anterior mediastinal lymphadenopathy. A tissue biopsy was obtained from the left atrial mass via a salvage left Chamberlain procedure and the histopathological sample confirmed an invasive thymoma (oval/spindle shaped cells with bland nuclei positive for cytokeratin, CD3, CD5, CD99 and Ki67.). The patient's hospital course was complicated by bradyarrythmia, hypotension and eventually death. Autopsy findings included a 13 cm thymoma extending to the level of the superior and anterior mediastinum, compressing the left main bronchus, encasing the great vessels and coronary arteries, and invading the left and right atria. Extrathoracic metastasis was present in the liver. Final staging according to the Masaoka Classification was malignant thymoma Stage IV B.
DISCUSSIONS: In general, metastatic tumors to the heart are more common than primary cardiac neoplasms. They are seen in approximately 10–15% of autopsy patients with invasive cancers. The most common malignancies that metastasize to the heart are lung and breast carcinoma, malignant melanoma, lymphoma, and leukemia. They reach the heart by lymphatic and hematogenous spread or by direct invasion. Metastatic disease of the heart can present with congestive heart failure, pericarditis, or with an arrhythmia. Metastatic involvement of the coronary vessels is extremely rare. We report a case of invasive thymoma to the myocardium and coronary vessels resulting in acute STEMI. To our knowledge, this is the first reported case of coronary vessel involvement by an invasive thymoma. Thymoma is the most common primary tumors of the anterior mediastinum. One third of thymomas are invasive. Invasive thymomas most commonly involve the pleura, pericardium, lungs, and recurrent laryngeal nerve. Cardiac metastasis is rare. Invasive thymomas are often slow growing. Optimal therapy depends on the stage of the tumor. It is thought that surgical resection and radiation alone are not effective for management of Stage IV B tumors. A multidisciplinary approach has been proposed with the use of surgical resection and a combination of chemo, radio, and steroid therapy. STEMI is predominately caused by coronary artery atherosclerotic plaque rupture and subsequent occlusive thrombus formation. This illustrates yet another mechanism of acute vessel occlusion by external compression of the coronary arteries. Tumor debulking and subsequent bypass grafting would be the preferred strategy in this situation.
CONCLUSION: In conclusion, this case represents two rare phenomena namely invasive thymoma and external compression of a native coronary vessel resulting in myocardial infarction.
DISCLOSURE: Pooja Raju, None.