Post-Transplant CMV Glomerulitis

The Banff 2022 Kidney Meeting Report: Reappraisal of microvascular inflammation and the role of biopsy-based transcript diagnostics

The XVI-th Banff Meeting for Allograft Pathology was held at Banff, Alberta, Canada, from 19th to 23rd September 2022, as a joint meeting with the Canadian Society of Transplantation. To mark the 30th anniversary of the first Banff Classification, premeeting discussions were held on the past, present, and future of the Banff Classification. This report is a summary of the meeting highlights that were most important in terms of their effect on the Classification, including discussions around microvascular inflammation and biopsy-based transcript analysis for diagnosis. In a postmeeting survey, agreement was reached on the delineation of the following phenotypes: (1) "Probable antibody-mediated rejection (AMR)," which represents donor-specific antibodies (DSA)-positive cases with some histologic features of AMR but below current thresholds for a definitive AMR diagnosis; and (2) "Microvascular inflammation, DSA-negative and C4d-negative," a phenotype of unclear cause requiring further study, which represents cases with microvascular inflammation not explained by DSA. Although biopsy-based transcript diagnostics are considered promising and remain an integral part of the Banff Classification (limited to diagnosis of AMR), further work needs to be done to agree on the exact classifiers, thresholds, and clinical context of use.

Approach to acute kidney injury following paediatric kidney transplant

PURPOSE OF REVIEW

In a child with evidence of acute kidney injury (AKI) following renal transplantation, it is important to quickly and accurately diagnose the cause to enable timely initiation of therapeutic interventions. The following article will discuss the differential diagnosis of acute graft dysfunction in paediatric kidney transplant recipients. This review will systematically guide the clinician through the common and less common causes and provide updates on current treatments.

RECENT FINDINGS

In patients with signs of graft dysfunction, rejection is an important cause to consider. Diagnosis of rejection relies on biopsy findings, an invasive and costly technique. Over the past 5 years, there has been a focus on noninvasive methods of diagnosing rejection, including serum and urinary biomarkers.

SUMMARY

This review discusses the differential diagnosis of acute graft dysfunction following transplant, with a focus on acute rejection, urinary tract infections and common viral causes, prerenal and postrenal causes, nephrotoxic medications, specifically calcineurin inhibitor toxicity, thrombotic microangiopathy and recurrence of the underlying disease. Each condition is discussed in detail, with a focus on clinical clues to the cause, incidence in the paediatric population, workup and treatment.

Cytomegalovirus nephritis in kidney transplant recipients: Epidemiology and outcomes of an uncommon diagnosis

BACKGROUND

Data on epidemiology and outcomes of cytomegalovirus (CMV) nephritis in kidney transplant patients are limited due to the rarity of this condition.

METHODS

A retrospective review of all kidney transplant recipients (KTR) (n = 6490) and biopsy-proven CMV nephritis between 1/1997 and 12/2020 was performed.

RESULTS

The prevalence of CMV nephritis was low: 13/6490 (0.2%). The diagnosis was made at a median of 7.0 months (range 2.6-15.6 months) after transplant. 6 of 13 (46%) patients were CMV (D+/R-). Median CMV DNA load at biopsy was 376,000, IU/mL (range 87,000-6,460,000 IU/mL). Main biopsy features were CMV glomerulitis (n = 7/13, 54%) followed by CMV tubulointerstitial nephritis (6/13; 46%). Mean eGFR at biopsy (22.7 ± 12 mL/min/1.73 m² ) was significantly decreased compared to baseline eGFR (38.7 ± 18.5 mL/min/1.73 m² , p = 0.02). The vast majority, 11 of 13 (85%), experienced graft failure including 5 of 13 (38%) death-censored. 5 of 13 (38%) patients were diagnosed with acute rejection: three had concurrent acute rejection, and two had rejection within 3 months of index biopsy, respectively. Patients with tubulointerstitial CMV nephritis were significantly more likely to have rejection at the time of biopsy (50% vs. 0%, p < 0.05) compared to those with glomerular CMV nephritis. There were no significant differences between these groups in terms of eGFR at all time points, death, graft failure, immunosuppression changes or rejection after biopsy.

CONCLUSION

CMV nephritis is rare but appears to be associated with poor patient/allograft outcomes. Early identification and timely treatment of CMV infection may prevent end-organ involvement and improve patient and allograft-related outcomes.