Combined Flow-Fluorescence in situ hybridization to HHV-8 and EBV reveals the viral heterogeneity of primary effusion lymphoma.

Primary effusion lymphoma (PEL) is a rare B-cell non-Hodgkin lymphoma associated with Kaposi Sarcoma-associated herpesvirus (KSHV/HHV8) infection. Lymphoma cells are coinfected with Epstein-Barr virus (EBV) in 60-80% of cases. Tools allowing a reliable PEL diagnosis are lacking. This study reports PEL diagnosis in 4 patients using a Flow-Fluorescence in situ hybridization (FlowFISH) technique that allowed detection of differentially expressed EBV and HHV8 transcripts within the same sample, revealing viral heterogeneity of the disease. Moreover, infected cells exhibited variable expressions of CD19, CD38, CD40, and CD138. Therefore, FlowFISH is a promising tool to diagnose and characterize complex viral lymphoproliferations.

Carfilzomib-associated thrombotic microangiopathy: clinical features and outcomes.

BACKGROUND AND HYPOTHESIS: Carfilzomib, a new proteasome inhibitor indicated for patients with relapsed/refractory myeloma, has been associated with cases of thrombotic microangiopathy (CFZ-TMA). The role of variants in the complement alternative pathway and therapeutic potential of complement blockade with eculizumab remain to be determined. METHODS: We report 37 cases of CFZ-TMA recorded in the French reference center for TMA with their clinical characteristics, genetic analysis and outcome according to treatments. RESULTS: A trigger was identified in more than half of cases, including 8 influenza and 5 SARS-CoV-2 cases. All patients presented with acute kidney injury (AKI) (KDIGO stage 3 in 31 (84%) patients) while neurological (n=13, 36%) and cardiac damage (n=7, 19%) were less frequent. ADAMTS13 and complement activity were normal (n= 28 and 18 patients tested) and no pathogenic variant in the alternative complement pathway was found in 7 patients tested.TMA resolved in most (n=34, 94%) patients but 12 (44%) still displayed stage 3 AKI at discharge. Nineteen (51%) patients were treated with therapeutic plasma exchange, 14 (38%) patients received corticosteroids and 18 (50%) were treated with eculizumab. However none of these treatments demonstrated a significant impact on outcomes. CONCLUSION: This study is the largest case series of CFZ-TMA since its approval in 2012. Patients present with severe AKI and experience frequent sequelae. Complement variants and blockade therapy do not seem to play a role in the pathophysiology and prognosis of the disease.

Characteristics of circulating KSHV-infected viroblasts during active KSHV+ multicentric Castleman disease.

Kaposi sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8-associated multicentric Castleman disease (MCD) is a polyclonal B-cell lymphoproliferative disorder that mainly occurs in immunocompromised hosts. The diagnosis relies on lymph node biopsy demonstrating KSHV-infected cells located in the mantle zone with a marked interfollicular plasma cell infiltration. Infected cells are large cells positive for immunoglobulin M (IgM), λ light chain, and CD38, described initially as infected plasmablasts. We show that IgM+λ+CD38high cells were also detectable in the peripheral blood of 14 out of 18 (78%) patients with active KSHV-MCD and absent in 40 controls. Using immunofluorescence and flow-fluorescence in situ hybridization, we demonstrate that these cells are KSHV infected and express both latent and lytic KSHV transcripts. These KSHV-infected viroblasts (KIVs) harbor a distinct phenotype compared with conventional plasmablasts. We also identified several putative mechanisms of immune escape used by KSHV, because KIVs displayed an overall decrease of costimulatory molecules, with a remarkable lack of CD40 expression and are interleukin-10-producing cells. The identification of this specific and easily accessible KSHV+ circulating population brings new elements to the understanding of KSHV-MCD but also raises new questions that need to be clarified.