ABSTRACT
Introduction: We report a rare case of an 80-year-old male patient with acute transformation of myelodysplastic syndrome (MDS) in the pericardial cavity, leading to cardiac tamponade. Case presentation: The patient had been diagnosed with MDS 7 months prior. One day before presentation, he suddenly developed dyspnea. At presentation, his blood pressure was stable, but he was in tachycardic atrial fibrillation; echocardiography revealed a pericardial effusion. Aortic dissection and acute myocardial infarction were excluded by examination upon admission. His blood pressure subsequently dropped, indicating pericardial tamponade. Pericardiocentesis was performed, and 800 ml of bloody pericardial fluid were withdrawn, stabilizing his blood pressure. The blasts ratio was higher in the pericardial fluid than in the periphera blood; bone marrow examination revealed no evidence of acute transformation, but the presence of numerous cells with chromosomal abnormalities in the pericardial sac cavity confirmed acute MDS transformation. The patient died on day 15 due to progressive multiorgan failure. The autopsy revealed a neoplastic lesion extending circumferentially throughout the epicardium. Conclusions: When a patient with an acute onset history of hematogenous pericardial effusion is found to have a pericardial tamponade of cancerous origin, acute transformation of MDS should be considered in the differential diagnosis.