An Unusual Contrast Computed Tomography Scan Finding in a Patient with Immune Checkpoint Inhibitor–Associated AKI

What is it about?

ICIs are widely used to treat many cancers; however, immune-related adverse events (irAEs) are known to occur. Kidney irAEs are rare; nonetheless, acute TIN remains the most common.1 A kidney biopsy is essential for identifying ICI-related AKI. However, kidney biopsies are not appropriate for diagnosing all cases; thus, the clinical diagnosis thereof is made and treatment is frequently empirically administered, without a biopsy.2 Recent studies have revealed that 18F-fluorodeoxyglucose–positron emission tomography is useful for diagnosing kidney irAEs.3 However, these are complex due to the significant costs involved. In our case, contrast-enhanced CT was incidentally performed, when the SCr was 1.14 mg/dL, revealing ill-defined, wedge-shaped, hypodense lesions in both kidneys. These findings are commonly associated with conditions, including immunoglobulin G4-related disease and acute focal bacterial nephritis. To the best of our knowledge, similar CT findings, in patients with kidney irAEs have only been reported in one other case.3 Contrast-enhanced CT is often avoided in the setting of AKI due to kidney irAE and is therefore rarely reported. Three-months post-discontinuation of the ICI, the histopathological analysis of the renal biopsy revealed focal inflammatory cellular infiltration of the interstitium, corroborating the CT findings. These histopathological analytical and imaging findings may help us to understand the etiology of kidney irAEs.

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