Multimodal imaging changed clinical decision-making: A rare mediastinal yolk sac tumor infiltrating the heart and follow-up.

Background: Primary yolk sac tumor of the mediastinum is an extremely rare and highly malignant neoplasm, affecting mainly young men.
Method and Result: This case report describes a 60-year-old man with a mediastinal yolk sac tumor and infiltrating the heart. A large mobile mass was found in the right atrium by transthoracic echocardiography, and myxoma was suspected. However, contrast-enhanced ultrasonography imaging revealed a remarkable enhancement in the mass. Highly metabolized mass was not only found in the right atrium, also in superior vena cava and right superior mediastinum by whole-body positron emission tomography-computed tomography. Supraclavicular lymph node biopsy confirmed the tumor as a primary mediastinum yolk sac. The tumor started to shrink during chemotherapy and AFP levels decreased. This patient significantly benefited from the chemotherapy.
Conclusion: Multimodal imaging plays a vital role in the diagnostic workup and management for cardiac mass.
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