No regression of renal amyloid mass despite remission of nephrotic syndrome in a patient with TRAPS following etanercept therapy.

Reactive systemic (AA) amyloidosis leading to renal failure is the most severe complication of tumor necrosis factor receptor-associated periodic syndrome (TRAPS). There is now growing evidence to suggest that anti-tumor necrosis factor (anti-TNF) agents may be an attractive treatment option for amyloidosis not only in TRAPS but in several forms of secondary amyloidosis complicating inflammatory rheumatic diseases. In most of the reported cases, anti-TNF agents were deemed successful on the basis of regression of proteinuria and either improvement or stabilization of creatinine clearance, while objective proof of renal amyloid regression either by serum amyloid P scintigraphy or biopsy is limited. We herein report a case of TRAPS complicated with nephrotic syndrome due to AA amyloidosis in which treatment with etanercept was associated with remission of the nephrotic syndrome but no regression of amyloid mass on the follow-up renal biopsy. Indeed, amyloid deposition was noted to be more pronounced on the second renal biopsy, particularly at tubular basement membranes. Although the variable relation between reduction in amyloid load and changes in organ function is well-known, the basis for renal recovery in association with stable or even progressive amyloid deposition is challenging. We suggest that in patients with secondary AA amyloidosis, mechanisms other than the reduction of amyloid mass could have contributed to the observed improvement of renal function with anti-TNF agents.