Positron emission tomography as an adjuvant diagnostic test in the evaluation of checkpoint inhibitor-associated acute interstitial nephritis

Abstract

BackgroundAcute interstitial nephritis is an immune-related adverse event that can occur in patients receiving immune checkpoint inhibitor therapy. Differentiating checkpoint inhibitor-associated acute interstitial nephritis from other causes of acute kidney injury in patients with cancer is challenging and can lead to diagnostic delays and/or unwarranted immunosuppression. In this case report, we assess the use of 18F-flourodeoxyglucose positron-emission tomography imaging as an alternative diagnostic modality in the evaluation of potential acute interstitial nephritis.Case presentationA 55-year-old woman with metastatic vulvar melanoma underwent treatment with two cycles of ipilimumab plus nivolumab, followed by seven cycles of nivolumab combined with radiation therapy. During her treatment, she developed non-oliguric acute kidney injury to a creatinine of 4.5 mg/dL from a baseline of 0.5 mg/dL. A clinical diagnosis of acute interstitial nephritis was made, and steroids were initiated, with rapid improvement of her acute kidney injury. Retrospectively, four positron-emission tomography scans obtained for cancer staging purposes were reviewed. We found a markedly increased 18F-flourodeoxyglucose uptake in the renal cortex at the time acute interstitial nephritis was diagnosed compared to baseline. In three cases of acute kidney injury due to alternative causes there was no increase in 18F-flourodeoxyglucose uptake from baseline.ConclusionsTo our knowledge, this is the first report describing increased 18F-flourodeoxyglucose uptake in the renal cortex in a patient with checkpoint inhibitor-associated acute interstitial nephritis. Our findings suggest that 18F-flourodeoxyglucose positron-emission tomography may be a valuable test for diagnosing immune-mediated nephritis, particularly in patients where timely kidney biopsy is not feasible.

Renal injury in the setting of immune checkpoint inhibitor: Report of a case of hypothyroidism and the role of positron emission tomography

“…Qualls and colleagues recently published a case of ICI-induced AIN. 8 In the report, it was stated that activity in the cortex of the kidney was not increased in three patients with AKI due to non-inflammatory conditions in the setting of ICI. In addition, their patient with AIN was non-oliguric, which leads to a more reliable assessment of the activity by PET-CT in the kidney.…”

Immune Checkpoint Inhibitors and Immune-Related Adverse Renal Events

“…Imaging studies, such as positron emission tomography–computed tomography scan has been reported as a potential diagnostic tool for ICI-associated AIN. 44 , 45 Although this diagnostic imaging test may be useful in cases with significant AKI from AIN, it may not be helpful in the mild AIN cases, especially if a baseline positron emission tomography–computed tomography scan before ICI treatment is not available for comparison. Importantly, mild 18 F-flourodeoxyglucose uptake has been observed in other non-AIN causes of AKI from ICIs.…”

“…Importantly, mild 18 F-flourodeoxyglucose uptake has been observed in other non-AIN causes of AKI from ICIs. 45 , 46 Therefore, clinicians should use this test judiciously with familiarity of its limitations. For those patients who have kidney biopsy contraindication, positron emission tomography–computed tomography scan may assist with a presumptive diagnosis of ICI-associated AIN when other causes of AKI have been ruled out.…”

Renal Complications Related to Checkpoint Inhibitors: Diagnostic and Therapeutic Strategies

“…Recently, an increase in 18F-flourodeoxyglucose uptake in the renal cortex in a patient with checkpoint inhibitor-associated acute interstitial nephritis was described in a case report. This suggests that 18F-flourodeoxyglucose positron-emission tomography could be a valuable diagnostic test for immune-mediated nephritis, particularly in patients where a timely kidney biopsy is not feasible [ 44 ].…”