Introduction: Thyroid hormones influence multiple systems, but most often the impact on the cardiovascular system is what brings the patient to the emergency department. Basedow’s disease, an autoimmune condition, is one of the most common causes of hyperthyroidism. The purpose of this presentation is to raise attention to an extracardiac cause that can lead to cardiac failure. Case presentation: A 55-year-old woman presented to our cardiology service with rapid palpitations, shortness of breath on small efforts, and extreme fatigue. The electrocardiogram revealed sinus tachycardia with a heart rate of 144 beats per min. Paraclinical investigations and a multidisciplinary team consultation led to a diagnosis of thyrotoxicosis due to Basedow’s disease. Following the initiation of cardiological and endocrinological treatments, the patient’s condition improved. Conclusion: Although hyperthyroidism is an extracardiac cause, it brought the patient to the cardiology emergency service for heart failure symptoms. The key to achieving a correct diagnosis and determining an optimal treatment lies in the multidisciplinary approach of pathology.

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 Pericardiocentesis was performed, and 800 ml of bloody pericardial fluid were withdrawn, stabilizing his blood pressure.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.