Dilemma of seronegative lupus nephritis: A case report of diffuse proliferative glomerulonephritis with thrombotic microangiopathyYuxuan Wu1, Qiaoyu Wang1, Haiyan Zhang2, Jianhua Qin1*, Weihua Wu1*1Department of Nephrology,Affiliated Hospital of Southwest Medical University; Sichuan Clinical Research Center for Nephropathy; Metabolic Vascular Disease Key Laboratory, Luzhou, Sichuan, China