PAX5 functions as a tumor suppressor by RB-E2F-mediated cell cycle arrest in Kaposi sarcoma-associated herpesvirus-infected primary effusion lymphoma.

Primary effusion lymphoma (PEL) is a malignant B-cell lymphoma attributable to Kaposi sarcoma-associated herpesvirus (KSHV) infection. PEL is characterized by invasive behavior, showing recurrent effusions in body cavities. The clinical outcome and typical prognosis in patients with PEL are poor and potentially lethal. Clarification of the pathogenesis in PEL is urgently needed in order to develop novel therapies. PEL cells generally lack B-cell surface markers, and we therefore hypothesized that the B-cell transcription factor, PAX5, would be down-regulated in PEL. The expression of PAX5 is detected from the pro-B to the mature B-cell stage and is indispensable for the differentiation of B-cells. PAX5 was silenced in PEL cells via its promoter methylation. Up-regulation of PAX5 induced several genes coding for B-cell surface marker mRNA, but not protein level. PAX5 inhibited cell growth via G1 cell cycle arrest. PAX5 bound to RB and increased its protein expression. RB/E2F-regulated genes were significantly down-regulated in microarray analysis and PCR experiments. To elucidate the in vivo role of PAX5, we examined the restoration of PAX5 in a PEL mouse model. The ascites volume and organ invasions were significantly suppressed by PAX5 restoration. Reduction of PAX5 has played a crucial role in the oncogenesis of PEL, and PAX5 is a tumor suppressor in PEL. Targeting PAX5 could represent a novel therapeutic strategy for patients with PEL.

Outcomes in Kaposi's sarcoma-associated herpesvirus -associated primary effusion lymphoma and multicentric Castleman's disease in patients with human immunodeficiency virus (HIV) in a safety-net hospital system.

OBJECTIVE: To describe cases of Kaposi's sarcoma-associated herpesvirus (KSHV)-associated multicentric Castleman's disease (MCD) and primary effusion lymphoma (PEL) in patients with HIV from a large, safety-net hospital system in Dallas, Texas, USA. METHODS: We conducted a retrospective review of patients with HIV-associated PEL and/or MCD. RESULTS: Twelve patients with PEL and 10 patients with MCD were identified. All patients were male and 17 of 20 were men who have sex with men; 66.7% of PEL patients and 50% of MCD patients had concurrent KS at the time of diagnosis; 42% of patients with PEL and 20% of patients with MCD died during the follow-up period. We noted improved survival in our cohort compared to previous studies, particularly in our PEL patients with a median survival of 11.4 months compared to 3-6-month median survival historically. Median follow-up time for MCD patients was 17.5 months. This improved survival is despite suboptimal antiretroviral therapy (ART) adherence at diagnosis, with only 50% of patients on ART at the time of MCD/PEL diagnosis. CONCLUSION: These data highlight the importance of early recognition of PEL and MCD, and the larger-scale efforts needed to better understand the pathogenetic drivers of clinical outcomes in patients affected by KSHV-related diseases.

Anticancer activities of parthenolide in primary effusion lymphoma preclinical models.

The sesquiterpene lactone parthenolide is a major component of the feverfew medicinal plant, Tanacetum parthenium. Parthenolide has been extensively studied for its anti-inflammatory and anticancer properties in several tumor models. Parthenolide's antitumor activities depend on several mechanisms but it is mainly known as an inhibitor of the nuclear factor-κB (NF-κB) pathway. This pathway is constitutively activated and induces cell survival in primary effusion lymphoma (PEL), a rare aggressive AIDS-related lymphoproliferative disorder that is commonly caused by the human herpesvirus 8 (HHV-8) infection. The aim of this study is to evaluate the targeted effect of Parthenolide both in vitro and in vivo. Herein, parthenolide significantly inhibited cell growth, induced G0 /G1 cell cycle arrest, and induced massive apoptosis in PEL cells and ascites. In addition, parthenolide inhibited the NF-ĸB pathway suppressing IĸB phosphorylation and p65 nuclear translocation. It also reduced the expression of the DNA methylase inhibitor (DNMT1). Parthenolide induced HHV-8 lytic gene expression without inhibiting latent viral gene expression. Importantly, DMAPT, the more soluble parthenolide prodrug, promoted delay in ascites development and prolonged the survival of PEL xenograft mice. This study supports the therapeutic use of parthenolide in PEL and encourages its further clinical development.

Developing new ceramide analogs and identifying novel sphingolipid-controlled genes against a virus-associated lymphoma.

Primary effusion lymphoma (PEL) is an aggressive malignancy with poor prognosis even under chemotherapy. Kaposi sarcoma-associated herpesvirus (KSHV), one of the human oncogenic viruses, is the principal causative agent. Currently, there is no specific treatment for PEL; therefore, developing new therapies is of great importance. Sphingolipid metabolism plays an important role in determining the fate of tumor cells. Our previous studies have demonstrated that there is a correlation between sphingolipid metabolism and KSHV+ tumor cell survival. To further develop sphingolipid metabolism-targeted therapy, after screening a series of newly synthesized ceramide analogs, here, we have identified compounds with effective anti-PEL activity. These compounds induce significant PEL apoptosis, cell-cycle arrest, and intracellular ceramide production through regulation of ceramide synthesizing or ceramide metabolizing enzymes and dramatically suppress tumor progression without visible toxicity in vivo. These new compounds also increase viral lytic gene expression in PEL cells. Our comparative transcriptomic analysis revealed their mechanisms of action for inducing PEL cell death and identified a subset of novel cellular genes, including AURKA and CDCA3, controlled by sphingolipid metabolism, and required for PEL survival with functional validation. These data provide the framework for the development of promising sphingolipid-based therapies against this virus-associated malignancy.

Genome-wide CRISPR screens reveal genetic mediators of cereblon modulator toxicity in primary effusion lymphoma.

Genome-wide CRISPR/Cas9 screens represent a powerful approach to studying mechanisms of drug action and resistance. Cereblon modulating agents (CMs) have recently emerged as candidates for therapeutic intervention in primary effusion lymphoma (PEL), a highly aggressive cancer caused by Kaposi's sarcoma-associated herpesvirus. CMs bind to cereblon (CRBN), the substrate receptor of the cullin-RING type E3 ubiquitin ligase CRL4CRBN, and thereby trigger the acquisition and proteasomal degradation of neosubstrates. Downstream mechanisms of CM toxicity are incompletely understood, however. To identify novel CM effectors and mechanisms of CM resistance, we performed positive selection CRISPR screens using 3 CMs with increasing toxicity in PEL: lenalidomide (LEN), pomalidomide (POM), and CC-122. Results identified several novel modulators of the activity of CRL4CRBN The number of genes whose inactivation confers resistance decreases with increasing CM efficacy. Only inactivation of CRBN conferred complete resistance to CC-122. Inactivation of the E2 ubiquitin conjugating enzyme UBE2G1 also conferred robust resistance against LEN and POM. Inactivation of additional genes, including the Nedd8-specific protease SENP8, conferred resistance to only LEN. SENP8 inactivation indirectly increased levels of unneddylated CUL4A/B, which limits CRL4CRBN activity in a dominant negative manner. Accordingly, sensitivity of SENP8-inactivated cells to LEN is restored by overexpression of CRBN. In sum, our screens identify several novel players in CRL4CRBN function and define pathways to CM resistance in PEL. These results provide rationale for increasing CM efficacy on patient relapse from a less-efficient CM. Identified genes could finally be developed as biomarkers to predict CM efficacy in PEL and other cancers.

High-dose Therapy and Autologous Hematopoietic Cell Transplantation as Consolidation Treatment for Primary Effusion Lymphoma.

BACKGROUND: Primary effusion lymphoma (PEL) is a rare type of non-Hodgkin lymphoma. The limited disease-free survival after chemotherapy has resulted in a poor prognosis. The outcomes data for high-dose therapy followed by autologous hematopoietic cell transplantation (auto-HCT) for PEL are limited owing to the rarity of the disease. PATIENTS AND METHODS: The present study included 9 patients with PEL from 2 major academic centers. Of these patients, 4 had received auto-HCT after high-dose therapy. Of the 9 patients, 8 (89%) had immunodeficiency (7 with human immunodeficiency virus seropositivity; 1, a solid organ transplant recipient) at the diagnosis. Human herpesvirus-8 by immunohistochemistry was positive in 8 patients. Anthracycline-based combination chemotherapy was used as first-line treatment in 7 patients; 4 underwent auto-HCT after attaining first complete remission. RESULTS: The median follow-up of the surviving patients was 25 months (95% confidence interval [CI], 8%-29%). The 2-year progression-free and overall survival for the 8 patients who had received treatment was 58% (95% CI, 22%-95%) and 73% (95% CI, 41%-100%), respectively. The 2-year progression-free and overall survival for the patients who had received auto-HCT was 50% (95% CI, 1%-99%) and 75% (95% CI, 33%-100%), respectively. Of the 4 auto-HCT recipients, all had been in first complete remission at the time of autografting. The cumulative incidence of relapse was 50% (95% CI, 19%-100%). No deaths were attributable to auto-HCT at 2 years after autografting. CONCLUSION: Despite the small sample size, our data have shown that consolidative auto-HCT is safe and effective and should be considered for eligible patients with PEL after demonstration of an objective response to induction chemotherapy. However, the high relapse rate remains a concern and warrants the development of new strategies to mitigate post-transplantation relapse.

Regulation of Virus-Associated Lymphoma Growth and Gene Expression by Bacterial Quorum-Sensing Molecules.

Kaposi's sarcoma-associated herpesvirus (KSHV) can cause several human cancers, including primary effusion lymphoma (PEL), which frequently occur in immunocompromised patients. KSHV-infected patients often suffer from polymicrobial infections caused by opportunistic bacterial pathogens. Therefore, it is crucial to understand how these coinfecting microorganisms or their secreted metabolites may affect KSHV infection and the pathogenesis of virus-associated malignancies. Quorum sensing (QS), a cell density-based intercellular communication system, employs extracellular diffusible signaling molecules to regulate bacterial virulence mechanisms in a wide range of bacterial pathogens, such as Pseudomonas aeruginosa, which is one of the most common opportunistic microorganisms found in immunocompromised individuals. In this study, we evaluated and compared the influence on PEL growth and the host/viral interactome of the major QS signaling molecules [N-(3-oxododecanoyl)-l-homoserine lactone (OdDHL), N-butyrylhomoserine lactone (BHL), and 2-heptyl-3-hydroxy-4-quinolone (PQS)] in conditioned medium from wild-type (wt) and QS mutant laboratory strains as well as clinical isolates of P. aeruginosa Our data indicate that P. aeruginosa coinfection may facilitate virus dissemination and establishment of new infection and further promote tumor development through effectively inducing viral lytic gene expression by its QS systems.IMPORTANCE Currently, most studies about KSHV infection and/or virus-associated malignancies depend on pure culture systems or immunodeficient animal models. However, the real situation should be much more complicated in KSHV-infected immunocompromised patients due to frequent polymicrobial infections. It is important to understand the interaction of KSHV and coinfecting microorganisms, especially opportunistic bacterial pathogens. Here we report for the first time that P. aeruginosa and its quorum-sensing signaling molecules display a complicated impact on KSHV-associated lymphoma growth as well as the intracellular host/viral gene expression profile. Our data imply that targeting of coinfecting pathogens is probably necessary during treatment of virus-associated malignancies in these immunocompromised patients.

EBV-positive PEL-like lymphoma that developed in the course of antisynthetase syndrome treated with tacrolimus.

Primary effusion lymphoma (PEL) is a rare type of extranodal lymphoma, typically of a B-cell origin, which presents as lymphomatous effusion with no nodal enlargement or tumor masses. The development PEL is universally associated with human herpes virus-8 (HHV-8) infection. Cases of HHV-8-negative primary lymphomatous effusion have recently been reported and referred to as HHV-8-unrelated PEL-like lymphoma. Some cases of this disease have been reported in iatrogenic immunocompromised patients. The mechanisms responsible for the inhibitory effects of the discontinuation of immunosuppressants other than methotrexate (MTX) against the disease, which have been demonstrated for MTX-associated lymphoproliferative disorders, have not yet been elucidated. We describe a case of PEL-like lymphoma that developed in the course of antisynthetase syndrome and was treated with tacrolimus. A single dose of systemic chemotherapy did not improve lymphomatous effusion, whereas the discontinuation of tacrolimus resulted in the long-term remission of this disease.

Oncolytic Reactivation of KSHV as a Therapeutic Approach for Primary Effusion Lymphoma.

Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma caused by Kaposi's sarcoma-associated herpesvirus (KSHV) infection. Currently, treatment options for patients with PEL are limited. Oncolytic viruses have been engineered as anticancer agents and have recently shown increased therapeutic promise. Similarly, lytic activation of endogenous viruses from latently infected tumor cells can also be applied as a cancer therapy. In theory, such a therapeutic strategy would induce oncolysis by viral replication, while simultaneously stimulating an immune response to viral lytic cycle antigens. We examined the combination of the FDA-approved drug ingenol-3-angelate (PEP005) with epigenetic drugs as a rational therapeutic approach for KSHV-mediated malignancies. JQ1, a bromodomain and extra terminal (BET) protein inhibitor, in combination with PEP005, not only robustly induced KSHV lytic replication, but also inhibited IL6 production from PEL cells. Using the dosages of these agents that were found to be effective in reactivating HIV (as a means to clear latent virus with highly active antiretroviral therapy), we were able to inhibit PEL growth in vitro and delay tumor growth in a PEL xenograft tumor model. KSHV reactivation was mediated by activation of the NF-κB pathway by PEP005, which led to increased occupancy of RNA polymerase II onto the KSHV genome. RNA-sequencing analysis further revealed cellular targets of PEP005, JQ1, and the synergistic effects of both. Thus, combination of PEP005 with a BET inhibitor may be considered as a rational therapeutic approach for the treatment of PEL. Mol Cancer Ther; 16(11); 2627-38. ©2017 AACR.

Post-transplant Lymphoproliferative Disorder Presented in a Form of Primary Effusion Lymphoma with t (8; 14).

Post-transplant lymphoproliferative disorders (PTLD) are emergent complications of organ transplantation occurring in 2% to 10% of transplanted patients. Epstein-Barr virus (EBV) infections are considered the most important factors for the development of these heterogeneous disorders. Primary effusion lymphoma (PEL) is a lymphoproliferative disorder predominantly described in patients with advanced AIDS and it is almost universally associated with human herpesvirus 8 (HHV8). In rare case, PEL also occurs in HHV8-negative patient, in the setting of hepatitis B and C virus infection. However, all these cases showed pan B-cell markers to be positive. Here, we report a case of PTLD presented as HHV8-negative and HIV-negative primary effusion lymphoma lacking near all lymphoid markers except PAX5 on immunohistochemistry, which created a diagnostic challenge. The diagnosis requires multiple approaches including molecular and genetic tests.

Persistent KSHV Infection Increases EBV-Associated Tumor Formation In Vivo via Enhanced EBV Lytic Gene Expression.

The human tumor viruses Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) establish persistent infections in B cells. KSHV is linked to primary effusion lymphoma (PEL), and 90% of PELs also contain EBV. Studies on persistent KSHV infection in vivo and the role of EBV co-infection in PEL development have been hampered by the absence of small animal models. We developed mice reconstituted with human immune system components as a model for KSHV infection and find that EBV/KSHV dual infection enhanced KSHV persistence and tumorigenesis. Dual-infected cells displayed a plasma cell-like gene expression pattern similar to PELs. KSHV persisted in EBV-transformed B cells and was associated with lytic EBV gene expression, resulting in increased tumor formation. Evidence of elevated lytic EBV replication was also found in EBV/KSHV dually infected lymphoproliferative disorders in humans. Our data suggest that KSHV augments EBV-associated tumorigenesis via stimulation of lytic EBV replication.

A role for MALT1 activity in Kaposi's sarcoma-associated herpes virus latency and growth of primary effusion lymphoma.

Primary effusion lymphoma (PEL) is an incurable malignancy that develops in immunodeficient patients as a consequence of latent infection of B-cells with Kaposi's sarcoma-associated herpes virus (KSHV). Malignant growth of KSHV-infected B cells requires the activity of the transcription factor nuclear factor (NF)-κB, which controls maintenance of viral latency and suppression of the viral lytic program. Here we show that the KSHV proteins K13 and K15 promote NF-κB activation via the protease mucosa-associated lymphoid tissue lymphoma translocation protein-1 (MALT1), a key driver of NF-κB activation in lymphocytes. Inhibition of the MALT1 protease activity induced a switch from the latent to the lytic stage of viral infection, and led to reduced growth and survival of PEL cell lines in vitro and in a xenograft model. These results demonstrate a key role for the proteolytic activity of MALT1 in PEL, and provide a rationale for the pharmacological targeting of MALT1 in PEL therapy.

Human Herpesvirus 8-Unrelated Primary Effusion Lymphoma-Like Lymphoma in an Elderly Korean Patient with a Good Response to Rituximab Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisolone.

Primary effusion lymphoma (PEL) is a rare type of non-Hodgkin's lymphoma arising from a B-cell lineage characterized by the formation of malignant effusion in body cavities without evidence of a detectable tumor. The effusion contains tumor cells universally infected with human herpesvirus 8 (HHV8), which is the critical factor differentiating PEL from HHV8-unrelated PEL-like lymphoma (PEL-LL). This report describes a 77-year-old male patient with pleural effusion and ascites, containing lymphoma cells expressing a B-cell phenotype, but without markers of HHV8 in immunocytochemical analysis. The patient was diagnosed with PEL-LL and treated with six cycles of rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP), which resulted in a complete remission. The patient is currently disease-free 15 months post-treatment. To the best of our knowledge, this is the first report on administration of R-CHOP in a PEL-LL patient in South Korea.

Management and Outcomes of HIV-Associated Primary Effusion Lymphoma: A Single Center Experience.

BACKGROUND: Primary effusion lymphoma (PEL) is a rare malignancy usually associated with HIV infection. Management and outcomes are poorly understood. METHODS: The medical records of all patients diagnosed with HIV-associated PEL at our institution between 1999 and 2014 were reviewed. Patients were followed till death, treatment failure or loss of follow-up. RESULTS: Twelve patients with PEL were identified during the 15 year study period; 9 had HIV infection. All 9 were male; median age was 45 years. All presented with local symptoms and were diagnosed with PEL a median of 11 years after HIV diagnosis. Location was pleural (3), pericardial (3), peritoneal (1) and extracavitatory (2). By definition, all had Ann Arbor stage 4 at diagnosis. Median follow-up was 34 months. Two patients had poor performance status and were unable to get chemotherapy. Seven patients had a complete remission (CR) and two died within 1 month of diagnosis. The median CD4 levels at PEL diagnosis in patients with poor versus good outcomes were 54 cells/mm3 (range, 26-82 cells/mm3) and 211 cells/mm3 (range, 73-800 cells/mm3). In contrast, the median lactate dehydrogenase (LDH) levels at PEL diagnosis with poor versus good prognosis were 1074 U/L (range, 703-1445 U/L) and 283 U/L (range, 156-760 U/L). CONCLUSIONS: Given its rarity, our knowledge of PEL relies solely on case reports and case series. Prompt HAART and chemotherapy may be effective in HIV- associated PEL and good outcomes are possible. LDH and CD4 may be possible prognostic factors in PEL.

Human Herpesvirus Type 8-associated Large B-cell Lymphoma: A Nonserous Extracavitary Variant of Primary Effusion Lymphoma in an HIV-infected Man: A Case Report and Review of the Literature.

BACKGROUND: Primary effusion lymphoma (PEL) is a rare non-Hodgkin lymphoma subtype primarily seen in human immunodeficiency virus (HIV)-infected individuals with low CD4(+) cell counts and elevated HIV viral loads. It has always been associated with human herpesvirus type 8 (HHV-8) and in 80% of cases has also been associated with Epstein-Barr virus (EBV). Less commonly, PEL has presented in patients with advanced age and other conditions associated with an altered immunity, including malignancy, liver cirrhosis, and immunosuppressive medications. It is a tumor of B-cell lineage; however, it shows a "null" phenotype, rarely expressing pan-B cell surface antigens. It will usually express CD45, CD30, CD38, CD138, and MUM1 and is characterized by lymphomatous effusions in body cavities but not lymphadenopathy. It is an aggressive lymphoma, with an average median survival of < 1 year. HHV-8-associated large B-cell lymphoma (HHV-8-LBL) is a second variant of PEL that is both solid and extracavitary. It has immunoblastic and/or anaplastic morphologic features and a distinct immunohistochemical staining pattern. It could also have a different clinical presentation than that of classic PEL. MATERIALS AND METHODS: We describe the case of a 57-year-old HIV-infected man who presented with a slow-growing and asymptomatic abdominal mass. Examination of an excisional biopsy specimen showed malignant large cells with prominent cytoplasm that were positive for pan-B cell antigen CD20, HHV-8, and EBV and negative for CD138, CD10, BCL-6, CD3, and CD30. The Ki-67 labeling index was 90%. The diagnosis was stage IIIA HHV-8-LBL, and he was treated with 6 cycles of R-EPOCH (rituximab, etoposide, vincristine, doxorubicin, cyclophosphamide, and prednisone) infusion chemotherapy. At 12 months after treatment, he was in complete remission. We also performed a Medline and Embase search to better understand the clinical findings of our patient and the unique attributes of HHV-8-LBL. Focusing our search on English language studies, we identified 83 cases of HHV-8-LBL without an effusion component. We compared these 83 cases with 118 reported cases of classic PEL. RESULTS: The median age of the patients with HHV-8-LBL was 41 years (range, 24-77), and 96% of the cases were associated with HIV. The median age of the patients with classic PEL was 41 years (range, 26-86), and 96% of the cases were associated with HIV. Of those with HHV-8-LBL, 31 of 61 (51%) had a pre-existing diagnosis of acquired immunodeficiency syndrome (AIDS) and 47 of 63 (75%) were coinfected with EBV. In contrast, 69 of 96 patients (72%) with classic PEL had a pre-existing AIDS diagnosis and 40 of 49 (82%) were coinfected with EBV. The mean CD4(+) count of the HHV-8-LBL patients was 256 cells/µL (range, 18-1126 cells/µL) compared with 139 cells/µL (range, 2-557 cells/µL) in the classic PEL patients. The median survival time for both groups was similar at 5.5 months (range, 25 days to ≥ 25 months) for patients with HHV-8-LBL and 4 months (range, 2 days to ≥ 113 months) for those with classic PEL. More patients with HHV-8-LBL were alive at the last follow-up point (59% vs. 18%). The percentage of patients achieving complete remission was 54% (30 of 56) and 36% (32 of 89) for HHV-8-LBL and classic PEL, respectively. CONCLUSION: Our patient's high CD4(+) cell count, the lack of a pre-existing AIDS diagnosis, and the excellent response to chemotherapy highlights that HHV-8-LBL might have distinct clinical features and possibly a better response to chemotherapy than classic PEL. HHV-8-LBL should be included in the differential diagnosis of HIV patients with solid lesions. It is essential that patients' Centers for Disease Control and Prevention HIV clinical status and HIV viral load at the diagnosis of PEL and HHV-8-LBL be reported and that the reported clinical results include longer term follow-up data. Only then will a more complete clinical picture of this little-appreciated and little-understood PEL variant be defined.

Primary Effusion Lymphoma (PEL)-Like Lymphoma in a Child With Congenital Immunodeficiency.

Primary effusion lymphoma (PEL) is a rare lymphoma that occurs more frequently in immunocompromised adults and has a poor survival. We report a 9-year-old female with combined immunodeficiency with an Epstein-Barr virus positive/human herpes virus 8 negative PEL-like lymphoma. The treatment with systemic chemotherapy for non-Hodgkin lymphoma, zidovudine, and interferon-α failed to control disease progression. This is the first reported pediatric case of PEL-like lymphoma. Increased diagnostic awareness and more effective treatment strategies are needed for this rare lymphoma.

Human herpesvirus-8-unrelated primary effusion lymphoma of the elderly not associated with an increased serum lactate dehydrogenase level: A benign sub-group of effusion lymphoma without chemotherapy.

Human herpesvirus-8-unrelated primary effusion lymphoma characterized by lymphomatous effusion without nodal lesions occasionally exhibits spontaneous remission. To elucidate the factors associated with a good prognosis, this study analyzed the clinical parameters of four patients treated in the department and 109 patients reported in case reports. The median age was 71 years and the median overall survival was 20 months. Patients possessing two independent favorable factors, an elderly status (≥ 70 years) and low serum lactate dehydrogenase (< 500 IU/L) showed a markedly higher 1-year survival than patients lacking either of the two factors in the absence of chemotherapy (94% vs 20%, p = 3 × 10(-5)), which was similarly observed in the chemotherapy group (94% vs 51%, p = 0.002). The use of rituximab was also a strong predictor of survival (89% vs 49%, p = 7 × 10(-6)). Elderly patients not exhibiting an increased lactate dehydrogenase may represent a benign sub-group of effusion lymphoma, which do not require chemotherapy to achieve remission.