Background: In kidney transplant patients, polyomavirus-associated nephropathy (PVAN) represents a serious complication; the key factor for the development of PVAN is immunosuppression level and modulation of anti-rejection treatment represents the first line of intervention. Allograft biopsy and histology remain the criterion standard for diagnosing PVAN. Methods: All consecutive renal biopsies with the diagnosis of PVAN carried out at the University Hospital City of Health and Science of Turin over a five-years period were studied. Renal allograft biopsy was performed due to renal function alterations associated to medium-high polyomavirus BK (BKV)-DNA levels on plasma specimen. Results: A total of 21 patients underwent a first biopsy to diagnose a possible BKV nephropathy, in 18, a second biopsy was made, in eight, a third biopsy, and finally, three underwent the fourth renal biopsy; following the results of each biopsies, immunosuppressant agents dosages were modified in order to reduce the effect of PVAN. Conclusions: In this study, the clinical and histological features of 21 kidney transplant recipients with BKV reactivation and development of PVAN are described. To date, the only treatment for PVAN consists in the reduction of immunosuppressive agents, constantly monitoring viral load.

中文翻译：

---

多瘤病毒BK肾病的同种异体肾活检：都灵移植中心，2015-19。

背景：在肾脏移植患者中，多瘤病毒相关性肾病（PVAN）代表严重的并发症。PVAN发生的关键因素是免疫抑制水平，抗排斥治疗的调节是干预的第一线。同种异体活检和组织学仍然是诊断PVAN的标准标准。方法：研究在都灵卫生与科学大学医院进行的为期五年的所有连续诊断为PVAN的肾脏活检。由于与血浆标本中高多瘤病毒BK（BKV）-DNA水平相关的肾功能改变，进行了肾脏异体移植活检。结果：总共21例患者进行了第一次活检，以诊断可能的BKV肾病；在18例中，进行了第二次活检，在8例中，进行了第三次活检，最后，3例接受了第四次肾脏活检。根据每次活检的结果，调整免疫抑制剂的剂量以降低PVAN的作用。结论：本研究描述了21例BKV激活和PVAN发展的肾移植受者的临床和组织学特征。迄今为止，PVAN的唯一治疗方法是减少免疫抑制剂，不断监测病毒载量。