History and findings: A 35-year-old man who, as a result of intravenous drug abuse, had become infected with HIV 18 years previously, was admitted with signs of right-heart failure. Three months earlier a systolic murmur had first been heard in the 5th intercostal space parasternally.
Investigations: Transesophageal echocardiography (TEE) demonstrated a 3 x 2 cm right atrial tumour, moderate to severe tricuspid regurgitation and pulmonary hypertension. Blood cultures grew Streptococcus.
Diagnosis, treatment and course: Endocarditis with atrial thrombi and recurrent pulmonary emboli was diagnosed and treated with antibiotics and anticoagulants. Three weeks later the TEE showed an increase in the atrial tumour. Computed tomography of skull, thorax and abdomen did not demonstrate any significantly enlarged lymph nodes. Exploratory thoracotomy revealed an infiltrating highly malignant centroblastic non-Hodgkin's lymphoma (NHL) of almost the entire free wall of the right atrium. After two courses of chemotherapy (CHOP protocol) the size of the tumour had significantly decreased.
Conclusion: The differential diagnosis of a right atrial tumour can be difficult in patients with HIV or AIDS. Even if the site is atypical and there is no lymphadenopathy, a lymphoma should be considered. In case of doubt a histological diagnosis via an exploratory thoracotomy should be performed.