Differences between κ and λ light chain amyloidosis analyzed by a pathologic scoring system.

Area of Science:

• Nephrology
• Pathology
• Immunology

Background:

• Amyloid light chain (AL) amyloidosis involves light chain proteins depositing in organs.
• AL-κ and AL-λ are subtypes of AL amyloidosis with shared histopathology.
• Differences in clinical and histological features between AL-κ and AL-λ remain unclear.

Purpose of the Study:

• To compare clinical manifestations, histologic findings, and clinical significance between AL-κ and AL-λ amyloidosis subtypes.
• To evaluate the utility of the composite scarring injury score (CSIS) and amyloid score (AS) in differentiating AL-κ and AL-λ.

Main Methods:

• Retrospective analysis of 94 kidney biopsies from patients with AL amyloidosis.
• Evaluation of biopsies using CSIS and AS.
• Comparison of scores and staining characteristics between AL-κ and AL-λ groups.

Main Results:

• The amyloid score (AS) was significantly higher in AL-κ than in AL-λ.
• Capillary wall and vascular amyloid components of AS were higher in AL-κ.
• Periodic acid-Schiff staining for amyloid was markedly higher in AL-κ; CSIS showed no significant difference between subtypes.

Conclusions:

• AL-κ amyloidosis exhibits a higher amyloid burden compared to AL-λ at the time of kidney biopsy.
• Higher serum creatinine and AS in AL-κ suggest a potentially worse prognosis.
• Findings provide a reference for clinical management of AL amyloidosis subtypes.