Polyomavirus nephropathy: diagnosis, histologic features, and differentiation from acute rejection

Area of Science:

• Nephrology
• Virology
• Transplantation Immunology

Background:

• Polyomaviruses, especially BK virus, establish latent infections, reactivating under immunosuppression in kidney transplant recipients.
• Reactivation can lead to polyomavirus nephropathy (PVN), a significant cause of graft dysfunction and loss.

Purpose of the Study:

• To review the diagnostic methods for PVN, including screening and definitive diagnosis.
• To discuss the histologic classifications of PVN and their correlation with clinical outcomes.
• To highlight the challenges in differentiating PVN from acute cell-mediated rejection.

Main Methods:

• Review of diagnostic tools: viruria and viremia levels for screening and presumptive diagnosis.
• Kidney biopsy for definitive PVN diagnosis.
• Analysis of histologic classifications based on viral load, fibrosis, and inflammation.

Main Results:

• Histologic classifications of PVN correlate with graft function, loss, treatment efficacy, and prognosis.
• Suggestive histologic features can help differentiate PVN from acute rejection, despite overlapping findings.

Conclusions:

• Accurate diagnosis and classification of PVN are crucial for managing kidney transplant recipients.
• Distinguishing PVN from acute rejection is essential for appropriate treatment and improved graft survival.