Unrelated Cord Blood Transplantation for EBV-associated Lymphoproliferative Disorders

Inclusion Criteria:General Inclusion Criteria: All subjects must meet all of the following criteria: Age range: 14 to 80 years old, inclusive. Diagnosed with an EBV-associated lymphoproliferative disease (including Chronic Active EBV Infection, EBV-associated Hemophagocytic Lymphohistiocytosis, and EBV-associated Lymphoma). Meet at least one of the following disease-specific criteria (see below). ECOG Performance Status score of 0-2 (or Lansky Play-Performance score ≥60 for children). Expected survival of ≥3 months. Signed informed consent form (for minors, consent must be provided by a legal guardian). Disease-Specific Inclusion Criteria: A. CAEBV Patients: Patients diagnosed with CAEBV according to the 2016 revised WHO classification criteria, who also meet all of the following: * Persistent or recurrent infectious mononucleosis-like symptoms for more than 3 months. * Elevated EBV-DNA load in peripheral blood or involved tissues (peripheral blood EBV-DNA \> 500 copies/ml). * Detection of EBV in T or NK cells (via EBER in situ hybridization or LMP1 immunohistochemistry). * Exclusion of other known immunodeficiency disorders, autoimmune diseases, or neoplastic diseases. B. EBV-HLH Patients: Meet ≥5 of the HLH-2004 diagnostic criteria: * Persistent or recurrent infectious mononucleosis-like symptoms for more than 3 months. * Fever ≥38.5°C. * Splenomegaly. * Cytopenias (affecting ≥2 of 3 lineages): * Hb \<90 g/L * PLT \<100 × 10⁹/L * ANC \<1.0 × 10⁹/L * Hypertriglyc…