Where has the lymphoma gone? Pericardial effusion adenosine deaminase may play a key role in diagnosing primary effusion lymphoma-like lymphoma: a case report

BACKGROUND: Primary effusion lymphoma (PEL) is a non-Hodgkin lymphoma that is exclusively generated by body cavity effusion. Primary effusion lymphoma develops in patients infected with human immunodeficiency virus (HIV) and is associated with the human herpes virus (HHV)-8 infection. However, there are sporadic cases without HHV-8 infections or any history of immunodeficiency, called ‘PEL-like lymphoma’. CASE SUMMARY: An 83-year-old man was admitted to our institution because of shortness of breath, fatigue, and facial oedema. Laboratory findings were unremarkable, including negative results for HIV antibodies. Transthoracic echocardiography revealed massive pericardial effusion surrounding the entire heart, which resulted in the early diastolic collapse of the right ventricular free wall, indicating elevated intra-pericardial pressure. He underwent pericardial centesis and 700 mL of pericardial fluid was drained. Adenosine deaminase (ADA) in the pericardial effusion showed an abnormally high value of 221 U/L. Cytological examination revealed a cellular population compatible with diffuse large B-cell lymphoma with prominent blastic characteristics and negative for HHV-8 latent nuclear antigens. Thus, the patient was diagnosed with HHV-8 unrelated HIV-negative PEL-like lymphoma. He was followed for more than 10 months in complete remission after a single pericardial drainage without any chemotherapy. DISCUSSION: Exhaustive drainage of the lymphomatous effusion may induce complete remission in some patients with PEL-like lymphoma. Furthermore, the ADA value in the pericardial effusion may serve as a valuable guide to facilitate the accurate diagnosis of PEL-like lymphoma.