Body Cavity-Based Lymphoma in a Country with Low Human Immunodeficiency Virus Prevalence: A Series of 17 Cases from the Consortium for Improving Survival of Lymphoma.

Purpose: Primary effusion lymphoma (PEL) is a type of body cavity-based lymphoma (BCBL). Most patients with PEL are severely immunocompromised and seropositive for human immunodeficiency virus (HIV). We investigated the distinctive clinicopathologic characteristics of BCBL in a country with low HIV burden.
Materials and Methods: We retrospectively collected data on the clinicopathologic characteristics, treatments, and outcomes of 17 consecutive patients with BCBL at nine institutions in Korea.
Results: Latency-associated nuclear antigen 1 (LANA1) immunostaining indicated that six patients had PEL, six patients had human herpesvirus 8 (HHV8)-unrelated BCBL, and five patients had HHV8-unknown BCBL. The patients with PEL exhibited no evidence of immunodeficiency except for one who was HIV positive. One (20%) and four (80%) patients with PEL and six (100%) and zero (0%) patients with HHV8-unrelated BCBL were positive for CD20 and CD30 expression, respectively. The two patients with PEL (one HIV-positive and one HIV-negative patient) with the lowest proliferation activity as assessed by the Ki-67 labeling index survived for > 1 and > 4 years without chemotherapy, respectively, in contrast to the PEL cases in the literature, which mostly showed a high proliferation index and poor survival.
Conclusion: PEL mostly occurred in ostensibly immunocompetent individuals and had a favorable outcome in Korea. A watchful waiting approach may be applicable for managing HIV-seronegative patients with PEL with a low Ki-67 labeling index. A possible trend was detected among LANA1, CD20, and CD30 expression in BCBL.