Low-Dose Liposomal Amphotericin B for Invasive Fungal Infection Prophylaxis in Neutropenic Children

Inclusion Criteria: * Age 3 to 17 years (inclusive), both sexes. * Meets NCCN 2025 V1 guideline criteria for high-risk invasive fungal disease, including allogeneic hematopoietic stem cell transplantation, autologous hematopoietic cell transplantation with mucosal damage, acute leukemia, grade 3/4 graft-versus-host disease, myelodysplastic syndrome, lymphoma(a), multiple myeloma(a), chronic lymphocytic leukemia(a), treatment with purine analogues (fludarabine, clofarabine, nelarabine), chimeric antigen receptor (CAR) T-cell therapy, alemtuzumab therapy, with expected neutropenia \>7 days(b) and accompanied by agranulocytosis. Note (a): For these heterogeneous diseases, myeloablative therapy must be met; if neutropenia \>7 days is not met, the patient should be excluded. Note (b): Agranulocytosis is defined as absolute neutrophil count ≤0.5×10\^9/L, or absolute neutrophil count ≤1×10\^9/L with expected decline to ≤0.5×10\^9/L within 48 hours. * Assessed by the study physician as having high-risk for invasive fungal infection, intolerant or unable to use other antifungal agents due to toxicity or other reasons, and the treating physician has independently decided in routine clinical practice to initiate liposomal amphotericin B for antifungal prophylaxis for 3-5 days, with the selected dosage regimen of 1 mg/kg/day, intravenous, once daily. * Patient or legally authorized representative has voluntarily signed the informed consent form. Exclusion Criteria: * Allergy to any component of liposomal amphotericin B, or development of serious adverse events during the initial 3-5 days of prophylactic use. * Prior history of proven or probable invasive fungal disease (IFD). * Presence of pneumonia, unexplained fever, or clinical/imaging evidence suggestive of or diagnosed as fungal infection during screening. * Clinically significant hypokalemia (defined as serum potassium \<3.2 mmol/L, or below the lower limit of normal while receiving digitalis therapy) that cannot be corrected before starting trial treatment. * Hepatic dysfunction with aspartate aminotransferase (AST) or alanine aminotransferase (ALT) ≥5× upper limit of normal (ULN), or total bilirubin ≥3× ULN. * Renal impairment requiring or currently undergoing hemodialysis or peritoneal dialysis. * New York Heart Association (NYHA) Class III/IV heart failure. * Positive for human immunodeficiency virus (HIV) antibody or Treponema pallidum hemagglutination assay (TPHA). * Expected survival \<3 months. * Pregnant or breastfeeding women, or women of childbearing potential who are not using contraception and planning pregnancy. * Any other condition that the investigator considers inappropriate for participation in the clinical trial.