HIV-negative primary effusion lymphoma: a series of seven cases

Primary effusion lymphoma (PEL) is a rare aggressive, human herpesvirus-8 (HHV8)-associated neoplasm of post-germinal centre B cell origin. It usually presents as a serous effusion in human immunodeficiency virus (HIV)-positive patients. PEL is rarely reported in HIV-negative patients.

wWe report seven cases of HIV-negative elderly men diagnosed with PEL in a single institution. Clinical information and laboratory characteristics were collected. All patients were men, with a mean age of 76 years (range = 60-93) and presented with pleural effusions (n = 6), pericardial effusion (n = 1) and/or ascites (n = 2); two patients had multiple effusions. Extracavitary tissue involvement was present in one patient, who was also a liver transplant recipient. All patients had a decreased blood lymphocyte fraction, with a zero CD4+ count in one. The tumour cells in cytology of effusions showed a moderate amount of cytoplasm, perinuclear hof (a focal area of clearing) and irregular nuclear outlines with coarse chromatin and prominent nucleoli. Immunohistochemically, PEL cells were positive for HHV8 latent nuclear antigen (7 of 7), CD45 (3 of 3), CD30 (4 of 4), MUM1/IRF4 (2 of 2) and were negative for CD3 and CD20 in all seven cases. CD138 was positive in six of seven cases. Epstein-Barr virus (EBV) was detected in two of seven cases by in-situ hybridisation. B cell clonality by polymerase chain reaction (PCR) was positive in two cases with adequate materials available. Conventional cytogenetic analysis showed complex karyotypes in three of five cases, with recurrent +8, +12 and t(4;12)(q27;q21), and one case with +7. Six of seven patients died of disease with a mean survival of 5.4 months (range = 0.4-11.2 months).

PEL can arise in immunocompetent, older patients, in this series all men, and behaves aggressively. These neoplasms are similar to their HIV-positive counterparts with anaplastic cytomorphology, HHV8 infection and a plasmablastic immunophenotype. The aetiology of PEL is uncertain, but may be related to physiological immunodeficiency associated with ageing.