Atypical case of AL amyloidosis with urinary erythrocyte casts

Area of Science:

• Nephrology
• Pathology
• Internal Medicine

Background:

• Erythrocyte casts in urinalysis typically signify glomerular inflammation, such as glomerulonephritis.
• Amyloid light-chain (AL) amyloidosis is a plasma cell dyscrasia that can lead to systemic amyloid deposition.
• Renal involvement in AL amyloidosis commonly presents with proteinuria and renal insufficiency.

Observation:

• A 73-year-old male presented with acute febrile illness, multiorgan dysfunction, renal failure, nephrotic-range proteinuria, microhematuria, and a rash.
• Urinary microscopy revealed numerous erythrocyte casts.
• Renal biopsy demonstrated AL amyloidosis and tubular injury, notably lacking signs of glomerular or vascular inflammation.

Findings:

• The presence of erythrocyte casts in this patient was not indicative of glomerulonephritis.
• Renal biopsy confirmed AL amyloidosis as the primary pathology despite the urinary findings.
• This case illustrates an atypical presentation of renal amyloidosis.

Implications:

• Diagnostic criteria for renal diseases should consider atypical presentations of amyloidosis.
• The association between erythrocyte casts and non-glomerular conditions like amyloidosis warrants further investigation.
• Understanding these unusual findings can improve diagnostic accuracy and patient management for rare kidney diseases.