Introduction: Primary cardiac lymphomas are very rare, representing only 0.5% of all lymphomas and 1-2% of all heart tumors. Cardiac involvement from systemic lymphomas is more common, comprising 10-20% of all lymphomas. Secondary cardiac lymphomas most frequently affect the pericardium, and then the myocardium. The patient’s symptoms are based on the area of cardiac involvement.

Case report: 79-year-old women was hospitalized due to shortness of breath, fatigue, and lower extremity edema. A transthoracic echocardiogram (TTE) showed a mass infiltrating the myocardium of the right atrium and the right ventricle causing systolic dysfunction of the right ventricle (TAPSE 5 mm, s’0.05 m/s). A thoracic computed tomography (CT) showed a mass in the anterior mediastinum, measuring 5 x 7.5 cm infiltrating the myocardium of the right atrium and ventricle. An endobronchal ultrasound (EBUS) guided biopsy was performed and tissue samples confirmed the diagnosis of diffuse large B cell lymphoma (DLBCL) of the mediastinum, bone marrow infiltration was nonexistent. Immunochemotherapy treatment (R-CEOP) was started and the patient’s symptoms significantly improved during the course of treatment. A follow-up thoracic CT showed that the mass had significantly reduced in size after 4 cycles of therapy, and now measuring 2.1 x 6.2 cm. A control TTE showed only moderate thickening of the right atrium and right ventricle myocardium (14 mm in width), with a normal systolic and diastolic RV function (TV E/A – 1.4).

Conclusion: In this case, the patient presented with signs and symptoms of right heart failure due to an infiltrating mass. Histology confirmed diagnosis of a DLBCL of the mediastinum. The patient was treated with immunochemotherapy, her symptoms improved, and by the end of treatment she was asymptomatic. The majority of the literature details patients with the rarer primary cardiac lymphoma. (1-3) The involvement of the right atrium and ventricle as a direct extension from an intrathoracic tumor mass in our patient resulted in a heavily impaired right heart systolic function, as a first symptom of the disease, and was completely resolved with treatment.