腎移植後BKウイルス腎症の1例

Abstract

30歳女性.血液型はO(Rh+)であった.血液型一致の母親をドナーとした生体腎移植後に血清Crの上昇を認め, ステロイドパルス療法を行うも腎機能は改善せず, 移植後274日目に再入院となった.入院時, PI, RI値は正常であったが, 尿細胞診にてdecoy cellを多数認め, PCR法では尿中・血中ともにBKVが検出された.以上より, BKウイルス腎症と診断し, 免疫抑制剤のMMFを減量し, γ-グロブリン投与を開始した.その後, 血清Cr値が上昇傾向を示したため, TACを減量, MMFを中止したところ, 血清Cr値は低下, 尿中decoy cellも陰性化し, 入院34日目(移植後307日目)に退院となった.退院5ヵ月(移植後456日目)にMMFを再開し, 現在, 移植腎機能も安定し, BKVNの再発も認められていない

BK virus nephropathy (BKVN) has emerged as an important cause of allograft dysfunction and loss in kidney transplant recipients. We present a case in a 30-year-old female who underwent ABO-compatible living kidney transplant from her mother and was maintained with tacrolimus, mycophenolate mofetil and prednisolone. The serum creatinine level was stabilized about 0.9 mg/dl on postoperative day (POD) 35. On POD258, the serum creatinine increased to 1.8 mg/dl and the patient received methylpredonisolone pulse therapy under the diagnosis of acute rejection, which resulted in further increase in creatinine level from 1.8 to 2.6 mg/dl. Urine cytology showed decoy cells, but renal biopsy specimen showed no evidence of viral infection. Despite histopathological findings, positive urine and serum BKV-DNA suggested that allograft dysfunction was caused by BKVN. Therefore, the immunosuppession was reduced and gamma-globuline was given for 2 weeks. After the treatment, urine cytology became negative for decoy cells and serum creatinine level recovered to 2.0 mg/dl. On POD456, serum creatinine level was stabilized about 1.8 mg/dl and decoy cells remained negative.