Primary effusion lymphoma in Taiwan shows two distinctive clinicopathological subtypes with rare human...

To investigate the clinicopathological and molecular features of primary effusion lymphoma (PEL) in Taiwan and the association with human immunodeficiency virus (HIV), human herpesvirus 8 (HHV8) and Epstein-Barr virus (EBV).

We investigated retrospectively 26 cases with a median age of 76.5. Only one (4%) patient was infected with HIV. Cytologically, all lymphoma cells revealed typical immunoblastic to plasmablastic morphology. Immunohistochemically, HHV8 was positive in eight (32%) tumours and negative in 17 (68%) cases. All 23 tested cases examined were of the non-germinal-centre B cell phenotype. MYC proto-oncogene (MYC) and Epstein-Barr encoding mRNA (EBER) were positive in 43% (nine of 21) and 17% (four of 23) cases, respectively. Immunoglobulin heavy chain (IGH), B cell lymphoma (BCL)2, BCL6 and MYC were rearranged in 71%, 11%, 12% and 18% cases, respectively. By univariate analysis, the overall survival (OS) was associated statistically with MYC expression (P = 0.012) and BCL2 rearrangement (P = 0.035), but not with the others. By multivariate analysis, no factor was statistically significant. Compared to the HHV8-negative cases, the HHV8-positive cases were mainly of the plasmablastic immunophenotype expressing CD30 and CD138, and with a less frequent expression of pan-B cell markers.

Apart from the phenotypical difference, our HHV8-positive neoplasms were not distinct from the HHV8-negative group. Literature review of 256 cases, including our cases, revealed that HHV8-positive cases were associated more frequently with HIV and EBV infection, with rare MYC rearrangement, and a poorer prognosis than HHV8-negative cases. We propose to name the HHV8-positive cases as 'classical' or 'type I PEL' and the HHV8-negative cases as 'type II PEL', stressing the similarities and the distinctive features between these two groups.