Abstract
Primary cardiac lymphoma is a rare disease with the potential to be fatal. This case reports a patient who developed primary cardiac lymphoma resulting in cardiac tamponade. Despite a compromised general condition, the lymphoma was diagnosed through a transvenous tumor biopsy. Chemotherapy led to significant improvement in the patient's condition. Malignant lymphoma can be treated with chemotherapy. Therefore, the performance of tumor biopsies even in patients with poor general condition enabled the initiation of treatment.