RESUMEN
BACKGROUND: Cardiac masses include various tumourous and non-tumourous lesions. Primary cardiac tumours are very rare and most commonly benign. Primary cardiac lymphomas (PCL) account for 1-2% of malignant primary cardiac tumours. Only 197 cases of PCL have been reported between 1949 and 2009. CASE SUMMARY: We report a case of a 73-year-old patient who presented with atrial flutter. The diagnosis was a tumourous cardiac mass in the right atrium with signs of the infiltration of the tricuspid valve insertion and pericardium. There were no signs of extracardiac disease at the initial presentation. The patient was deemed to be inoperable by cardiac surgeons. Rapid tumour progression caused atrioventricular-block type Mobitz 2 with concomitant obstruction of the tricuspid valve and axillary lymph node metastasizing. Excision of the axillary lymph node revealed a diffuse large B-cell non-Hodgkin lymphoma. An epicardial right ventricle single lead pacemaker was sited, and chemotherapy was administered, resulting in complete remission. DISCUSSION: Cardiac masses are rare and challenging cases. Although current imaging procedures deliver extensive information, histological examination is still required in many cases. We encountered a tumourous mass with deep infiltration. After the patient was deemed inoperable, later lymph node invasion allowed histological examination, revealing PCL. Primary cardiac lymphomas are life-threatening tumours with rapid and aggressive growth. Treatment is based on chemotherapy consisting of anthracycline-containing regimens. This case report highlights the curative potential of chemotherapy, as we report a rapid regression of the tumour as well as the disappearance of arrhythmias and conduction disorders after treatment.