Self-Limited Effusion Large B-Cell Lymphoma: Two Cases of Effusion Lymphoma Maintaining Remission after Drainage Alone

We report two cases of human herpesvirus-8 (HHV-8)-negative large B-cell lymphoma involving pericardial and/or pleural effusion that regressed after drainage alone. Case 1 is a 70-year-old man showing massive pericardial effusion. Cytology of the drained effusion showed monotonous infiltration of CD3-, CD20+, CD79a+, and CD138- large B-cells. Monoclonality was shown by Southern blot analysis. Case 2 is a 70-year-old man with massive pericardial and bilateral pleural effusion. Cytology of pericardial effusion showed infiltration of CD20+, CD45RO-, CD138-, immunoglobulin lambda chain+, and kappa chain- large B cells. In both cases, effusion resolved after drainage and no relapse has been observed. HHV-8 was not demonstrated in either case. Clinical presentation of our two cases resembled primary effusion lymphoma (PEL), but cytomorphology, immunophenotype, and prognosis were clearly distinct from those of PEL. HHV-8-negative effusion lymphomas might include prognostically favorable self-limited tumors that could regress without any cytotoxic therapy.