Abstract: SA-PO168
An Atypical Cause of Kidney Amyloidosis: Combined Heavy and Light-Chain Amyloidosis
Session Information
- Onconephrology: Kidney Outcomes during Cancer Treatment and Nephropathies
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1700 Onconephrology
Authors
- Gonzalez Hernandez, Dina R., MedStar Health, Baltimore, Maryland, United States
- Cervantes, C. Elena, Johns Hopkins University, Baltimore, Maryland, United States
Introduction
The kidney is the second most commonly affected organ in systemic amyloidosis. The International Society of Amyloidosis identifies 14 types of kidney-related amyloidosis, with most studies indicating that immunoglobulin (Ig) light chain (AL) amyloidosis is the predominant cause in over half of the cases. Heavy chain (AH) amyloidosis has been reported in 0.1 % to 2.3 % of kidney amyloidosis cases. However, combined heavy and light chain (AHL) amyloidosis is extremely rare.
Case Description
A 78-year-old man presented to the hospital with lower and upper extremities edema, dyspnea, and pulmonary edema. Workup revealed a serum creatinine of 1.25 mg/dL, and serum albumin of 2.7 g/dL. Urinalysis showed 3+ proteinuria with 22 g of proteinuria in a 24-hour collection. Serologic workup revealed high lambda light chains at 3,800 mg/L with kappa/lambda ratio of 0.01 and elevated IgM levels at 3,500 mg/L. A kidney biopsy showed mesangial expansion with negative periodic-acid-Schiff (Fig 1A) and positive Congo Red Stain (Fig 1B) with apple-green birefringence under polarized light. Immunofluorescence revealed diffuse mesangial staining for IgM (3+) (fig 1C), C3 (2+) and lambda light chains (2+). Mass spectrometry confirmed lambda light chain and mu heavy chain amyloidosis. The patient was diagnosed with AHL amyloidosis and initiated treatment with bendamustine and rituximab; however, his kidney disease progressed rapidly, necessitating dialysis initiation approximately 10 months after his initial presentation.
Discussion
AHL amyloidosis is extremely rare. Diagnosis requires a kidney biopsy and mass spectrometry to type the amyloidogenic protein given the highest sensitivity and specificity of this technique and the limitations of immunofluorescence. Compared to AL, AHL patients have a higher prevalence of IgM monoclonal gammopathy, longer overall survival (5-year survival rate of 66%), and less advanced disease. Although data are limited, our case underscores the potential rapid progression to dialysis in AHL patients with high proteinuria at diagnosis.