A clinicopathologic study of the spectrum of systemic forms of EBV‐associated T‐cell lymphoproliferative disorders of childhood: A single tertiary care pediatric institution experience in North America

Abstract Background Systemic forms of EBV‐associated T‐cell lymphoproliferative disorders of childhood (S‐EBV‐T‐LPD) comprise three major forms: EBV‐positive hemophagocytic lymphohistiocytosis (EBV‐HLH), systemic EBV‐positive T‐cell lymphoma (S‐EBV‐TCL), and systemic chronic active EBV infection (S‐CAEBV). These disorders occur rarely in children in Western countries. Here, we described eight children of such entities. Design Eight cases (six clinical and two autopsy) with S‐EBV‐T‐LPD of childhood were retrospectively identified from 1990 to 2015. Clinicopathologic parameters including histomorphology, immunophenotype, EBV studies, and T‐cell receptor gene rearrangement studies were recorded. Results Patients include five females and three males of Hispanic, Asian, and Caucasian origins with an age range of 14 months to 9 years. Fever, hepatosplenomegaly, cytopenias, abnormal EBV serologies, and very high EBV viral loads were common findings. Histologic findings showed EBV + T‐cell infiltrates with variable degrees of architectural distortion and cytologic atypia ranging from no to mild cytologic atypia to overt lymphoma and tissue hemophagocytosis. All showed aberrant CD4 + or CD8 + T cells with dim to absent CD5, CD7, and CD3, and bright CD2 and CD45 by flow cytometry or loss of CD5 by immunohistochemistry. TCR gene rearrangement studies showed monoclonal rearrangements in all clinical cases (6/6). Outcomes were poor with treatment consisting of chemotherapy per the HLH‐94 or HLH‐2004 protocols with or without bone marrow transplant. Conclusion In this large pediatric clinicopathologic study of S‐EBV‐T‐LPD of childhood in the United States, EBV‐HLH, S‐EBV‐TCL, and S‐CAEBV show many overlapping features. Diagnosis is challenging, and overall outcome is poor using current HLH‐directed therapies.