患儿，男，10岁，因造血干细胞移植后9个月，出现颜面水肿、蛋白尿2个月入院。临床诊断肾病综合征，经规范糖皮质激素治疗4周，尿蛋白未转阴，考虑激素耐药。行肾穿刺活检术，肾脏病理提示膜性肾病，质谱分析肾小球基底膜颗粒状IgG和信号蛋白 3B（semaphorin 3B, Sema 3B）共沉积，诊断为Sema 3B膜性肾病。给予糖皮质激素联合他克莫司治疗后，随访3个月，患儿尿蛋白明显减少，水肿消退，病情稳定，未出现复发。该病例提示儿童造血干细胞移植后可能出现Sema 3B膜性肾病，提示精准诊断在儿科肾病中的重要性，未来需多中心研究明确其病程和遗传易感性，开发特异性标志物和疗法，推动个体化治疗，改善患儿预后。

A 10-year-old boy was admitted with facial edema and proteinuria for two months, occurring nine months after hematopoietic stem cell transplantation. He was clinically diagnosed with nephrotic syndrome and showed no remission after four weeks of standard glucocorticoid therapy, suggesting steroid-resistant disease. Renal biopsy was consistent with membranous nephropathy. Mass spectrometry identified granular co-deposition of IgG and semaphorin 3B (Sema3B) along the glomerular basement membrane, establishing the diagnosis of Sema3B-associated membranous nephropathy. Treatment with glucocorticoids combined with tacrolimus led to a marked reduction in proteinuria, resolution of edema, and clinical stabilization over a three-month follow-up, with no recurrence. This case highlights that Sema3B-associated membranous nephropathy may occur after hematopoietic stem cell transplantation in children and underscores the importance of precise diagnostics in pediatric nephropathies. Future multicenter studies are needed to clarify disease course and genetic susceptibility, develop specific biomarkers and therapies, promote individualized treatment, and improve prognosis.