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Abstract: TH-PO523

Apolipoprotein A-IV Amyloidosis: An Unusual Cause of Renal Amyloidosis and CKD

Session Information

  • Trainee Case Reports - I
    October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 1903 CKD (Non-Dialysis): Mechanisms

Authors

  • Sheikh, Sadaf Noor, Washington university St Louis MO, Valley Park, Missouri, United States
  • Li, Tingting, Washington University in St. Louis, Saint Louis, Missouri, United States
  • Kunjal, Ryan A., Washington University, St Louis, Missouri, United States

Group or Team Name

  • WashU ,Nephrology
Introduction

Apolipoprotein A-IV associated amyloidosis (AApoAIV amyloidosis) is a rare cause of amyloidosis with only few reported cases in the literature. Renal AApoAIV amyloidosis histologically exhibits medullary involvement with sparing of the cortex. The diagnosis of renal AApoAIV amyloidosis requires a high degree of suspicion and examination of the renal medulla on renal biopsy. The definitive diagnosis is best established by mass spectrometry. Here we present two patients with renal AApoAIV amyloidosis.

Case Description

Case 1
Fifty-three-year-old white male with past medical history of well-controlled type 1 diabetes mellitus and hypertension presented with a 10-year history of slowly declining renal function (Serum creatinine 1.1 mg/dl 10 years ago and 1.7 mg/dl in 2018). Urinalysis was unremarkable and 24-hour urine collection showed 240 mg of protein. He was found to have a positive serum immunofixation with IgA kappa monoclonal protein and was diagnosed with IgA kappa smoldering myeloma by bone marrow biopsy. Subsequent renal biopsy showed multifocal, medullary deposition of amyloid of amyloid material. No similar deposits were seen within the renal cortex. Mass spectrometry surprisingly identified apolipoprotein A-IV amyloid deposition and no peptides were identified for any other types of amyloid. The smoldering myeloma was thought to be unrelated to the amyloid.


Case2
Sixty-Eight-year-old white female has had stage 3 CKD since 2009, when her serum creatinine was 1.4. Creatinine increased to 1.6 in 2016 and she underwent renal biopsy which showed a focal area of amyloid deposits in the medulla. Mass spectrometry identified the amyloid as Apolipoprotein A-IV. The patient's renal function has remained stable over the last 2 years.

Neither patient had extra-renal manifestations of amyloidosis or family history of amyloidosis.

Discussion

Apolipoprotein A-IV amyloidosis is a rare type of amyloidosis that seems to have a predilection for the kidney and is limited to the renal medulla. The limitations of the amyloid to the medulla correlates with the clinical findings of slow decline of renal function, unremarkable urinalysis, and no significant proteinuria. The pathogenesis of apolipoprotein A-IV amyloid formation is unknown. There are no known treatment options at this time and management is conservative.