Excerpt

A 61-year-old man was admitted to our hospital for further evaluation of a cardiac mass. He had complained of progressive exertional dyspnea for several weeks. Transthoracic echocardiogram revealed a large and inhomogeneous mass that filled the entire right atrium (RA) (Figure 1). Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) revealed abnormal accumulation in the RA tumor, superior mediastinal lymph nodes, and both right and left ventricles (Figure 2A–C). Cardiac magnetic resonance imaging (MRI) also revealed the presence of RA mass, and the signal intensity of this tumor is homogeneous isodensity on a T1 black-blood technique (BB); heterogeneous on T2 BB with an irregular and invasive contour with partial gadolinium enhancement (Figure 3). Based on these images, we suspected angiosarcoma.1 On the third hospital day, his symptoms worsened with presyncope due to rapid tumor growth. He underwent chemotherapy (paclitaxel and dexamethasone), resulting in gradually symptomatic improvement and shrinkage of the RA tumor. Posterolateral thoracotomy was performed for tumor biopsy; however, the specimens showed only necrotic tissues; therefore, we could not reach a definitive diagnosis. After 36 days, ¹⁸F-FDG PET was repeated for follow-up of the cardiac mass, which revealed abnormal focal uptakes in the heart and bilateral adrenal glands (Figure 2D–F). Biopsy of the left adrenal gland was performed, and pathology confirmed the diagnosis of diffuse large B-cell lymphoma. Thereafter, rituximab, cyclophosphamide, doxorubicin, vincristine, prednisolone therapy for lymphoma was started.

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