2. Case report
A 60-year-old previously healthy Japanese man was referred to our hospital for evaluation of anemia and pericardial effusion 13 months before his death. The patient presented with no apparent symptoms at that time. Pericardiocentesis was performed, and the effusion was evaluated cytologically; however, no atypical cells could be identified, and the etiology of the effusion was undefined. The patient ignored follow-up visit appointments; but returned six months later to the hospital with dyspnea, bloody sputum, edema, and anorexia. A blood examination showed severe anemia (red blood cells, 1.64 × 106/μL; hemoglobin, 3.3 g/dL), and echocardiography revealed a mass in the right atrium (Figure 1). Computed tomography (CT) disclosed multiple nodules in the lungs and the liver. As a biopsy of the cardiac mass was technically difficult, a transbronchial biopsy of the lung mass was performed; but the biopsied specimen did not contain any atypical cells. Hematological malignancies were suspected because of progressive anemia and the presence of human T-cell leukemia virus type 1 antibodies. The patient was treated with THP-COP (pirarubicin, cyclophosphamide, vincristine, and prednisolone) and mogamulizumab under the provisional diagnosis of adult T-cell leukemia/lymphoma. Nevertheless, the patient’s general condition worsened progressively. The anemia and edema continued to progress, and the pleural effusion increased. The patient died of respiratory failure 13 months after his initial admission to the hospital.
The patient was autopsied eight hours after his death. The heart adhered to the pericardium (Figure 2A), and the pericardial cavity contained 130 mL of sanguineous pericardial effusion. In the right atrium, a dark-red colored, approximately 7 × 4-cm-sized multilobulated tumor arose from the atrial wall and filled the dilated atrial lumen (Figure 2B). The cut surface of the tumor was sanguineous and solid, intermingled with necrotized and calcified foci (Figure 2C). The muscular layer of the right atrial wall was completely replaced by the tumor. The tumor penetrated the pericardium and directly invaded the right lung (Figure 2D). Histologically, the tumor consisted of atypical cells with oval- to spindle-shaped nuclei, which formed vague capillary channels containing red blood cells (Figure 3A). Tumor cells protruded into the atrial cavity, forming papillary structures (Figure 3B). Exfoliated clusters of tumor cells were also observed in the atrium. The tumor cells were immunoreactive for CD31 (Figure 3C) and FLI1 but were negative for podoplanin (D2-40 antibody). Therefore, we diagnosed the lesion as an angiosarcoma. The tumor cells penetrated the pericardium and visceral pleura of the right lung and directly invaded the pulmonary parenchyma. Multiple metastases were identified in the lungs, liver, spleen, jejunum, and skin. In the jejunum, the metastatic nodule resulted in intussusception. In the bilateral lungs, tumor emboli were formed in the pulmonary arteries, and intra-alveolar hemorrhage and bronchopneumonia were present. The central nervous system was not examined.