Primary cardiac lymphoma is a very rare tumor which commonly affects the right atrium, although any chamber may be affected. Over the past few decades, the incidence of the lesion has increased, due mainly to growing numbers of immunocompromised patients, either HIV-related or iatrogenic. Because of this rapid evolution, the situation represents an oncologic emergency, and therefore early diagnosis and treatment are crucial. Although MRI is the most sensitive modality, open biopsy remains the 'gold standard' for reaching the diagnosis. However, the overall prognosis is poor. Herein is presented a case of a large B-cell non-Hodgkin lymphoma involving only the aortic valve.