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Abstract: SA-PO208

The Meaningful Medulla: Apolipoprotein A-IV Amyloidosis

Session Information

Category: Onconephrology

  • 1700 Onconephrology


  • Hartsell, Sydney Elizabeth, University of Utah Health, Salt Lake City, Utah, United States
  • Revelo Penafiel, Monica Patricia, University of Utah Health, Salt Lake City, Utah, United States
  • Gilligan, Sarah, University of Utah Health, Salt Lake City, Utah, United States
  • Al-Rabadi, Laith, University of Utah Health, Salt Lake City, Utah, United States
  • Abraham, Josephine, University of Utah Health, Salt Lake City, Utah, United States

Apolipoprotein A-IV (ApoAIV) amyloidosis is a rare disease affecting the kidney. The few existing case reports cite limited proteinuria with renal decline. We report a case of ApoAIV amyloidosis presenting with acute renal failure and nephrotic range proteinuria.

Case Description

A 67-year-old man with a history of gout presented with 3 months of fatigue and leg swelling after mildly symptomatic COVID-19. Labs revealed a serum creatinine of 11.5 mg/dl, increased from 1.3 mg/dl at baseline. He had no diabetes or significant nonsteroidal use and no family history of renal disease. Urine protein-creatinine ratio was 4.7 g/g. Ultrasound showed increased renal echogenicity without obstruction. Renal biopsy sampled only medulla and revealed interstitial Congo red positive amyloid deposits without light chain clonality (Fig. a-c). He received a short steroid taper and started hemodialysis. Subsequent workup was notable for normal serum kappa:lambda light chain ratio, serum and urine electrophoresis, bone marrow biopsy, and PET/CT. A second renal biopsy sampled only cortex and showed focal and segmental glomerulosclerosis (FSGS) with incomplete podocyte effacement, 70% interstitial fibrosis and tubular atrophy (IFTA), moderate arterio- and arteriolosclerosis, and no amyloid deposits (Fig. d-f). Mass spectrometry of the medullary deposits showed ApoAIV amyloid. He remains on dialysis and has been listed for transplant.


ApoAIV amyloid is a rare cause of renal amyloidosis, often presenting as progressive kidney failure with minimal proteinuria. Renal pathology is notable for amyloid deposits restricted to the medulla with cortical sparing. This patient additionally showed chronic pathological changes and proteinuria here is presumed to be due secondary FSGS. This case highlights an unusual presentation with nephrotic syndrome and the importance of mass spectrometry for amyloid subtyping.

Figure: Biopsy Findings