The utility of repeat kidney biopsy in systemic immunoglobulin light chain amyloidosis

Abstract

Background: The diagnostic utility of repeat kidney biopsy in AL amyloidosis patients in complete (CR) or very good partial hematologic response (VGPR) but with renal organ relapse is not clear.

Methods: We present eight patients with AL amyloidosis who had a repeat kidney biopsy performed.

Results: AL amyloidosis was initially diagnosed by a kidney biopsy. All patients had a favorable response to treatment (CR/VGPR) and five of them also had initially a renal organ response. A repeat kidney biopsy was done due to gradual deterioration of kidney function and/or proteinuria while maintaining a hematologic response. Repeat kidney biopsies showed findings consistent with amyloid deposits in all patients. Seven patients had renal progression with four of them requiring dialysis initiation. Only one patient had a favorable renal outcome. This patient had subacute kidney injury with decreasing proteinuria and was found to have granulomatous interstitial nephritis in addition to amyloid deposits and responded well to steroid treatment with rapid improvement in renal function.

Conclusions: In AL amyloidosis patients who achieve a favorable hematologic response to treatment (CR/VGPR) but subsequently develop worsening renal insufficiency or proteinuria, a repeat kidney biopsy should generally not be performed. Amyloid deposits persist in the kidneys even after successful hematologic treatment and it is impossible to differentiate between new versus old amyloid deposits, which makes performing a repeat kidney biopsy unnecessary in most cases. Demonstration of amyloid deposits on repeat kidney biopsy would not aid in the decision making regarding re-initiation of hematologic treatment. A kidney biopsy should be considered only in cases when a specific alternative diagnosis is suspected.

Keywords:

• Systemic light chain amyloidosis
• kidney biopsy
• AL amyloidosis
• renal amyloidosis
• repeat biopsy

Acknowledgements

Portions of this article were presented in the 4th IKMG – International Kidney and Monoclonal Gammopathy Research Group, May 2019 in Montreal, Canada.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported in parts by funds provided by the McCaleb Award from the Amyloidosis Center, Boston University School of Medicine, Alan and Sandra Gerry Amyloid Research Laboratory (AA and AH) and NIH grant 1KO8DK090143 (AH).