Differences between kappa and lambda light chain amyloidosis analyzed by a pathologic scoring system

Objectives Amyloid light chain (AL)-kappa and AL-lambda share common histopathologic changes; however, the potential difference in clinical manifestations, histologic findings, and clinical significance between the 2 subtypes remain unclear. Methods In a retrospective study, 94 kidney biopsies for AL amyloidosis were evaluated using the composite scarring injury score (CSIS) and amyloid score (AS). Results were then compared between AL-kappa and AL-lambda. Results Comparing AS and CSIS between AL-kappa and AL-lambda, the AS was significantly higher in AL-kappa than in AL-lambda, with 2 components of AS (capillary wall and vascular amyloid) scoring higher in AL-kappa than in AL-lambda, while mesangial and interstitial ASs were similar in the 2 cohorts. In addition, the proportion of periodic acid-Schiff strong-staining amyloid in AL-kappa was markedly higher than in AL-lambda. There was no significant difference in CSIS and its components between the 2 subtypes of AL amyloidosis. Conclusions Overall, AL-kappa presents with higher serum creatinine and a higher AS score than AL-lambda at biopsy, which may indicate a worse prognosis and be an important reference for clinical management.