Long-term survival in systemic amyloid A amyloidosis complicating Crohn's disease.

Systemic AA amyloidosis is a serious and potentially fatal complication of Crohn's disease. Proteinuria is the most common presentation, but the diagnosis can only be confirmed by showing amyloid in the tissues and is often delayed. Recently, scintigraphy has been developed using 123I-serum amyloid P component (SAP) as a noninvasive and quantitative alternative to histology in which this nuclear medicine tracer specifically targets amyloid deposits in vivo. This study investigates 4 patients with Crohn's disease who, despite having only low-grade clinical activity, developed progressive AA amyloidosis and renal failure. One patient died while receiving hemodialysis, but in the other 3 cases, renal transplantation and standard antirejection therapy were associated with remission of inflammatory activity. Serial SAP scintigraphy showed regression of amyloid in 2 of these patients and absence of progression in the other. These case studies show the dynamic but variable behavior of AA deposits in different patients and show the use of radiolabeled SAP for diagnosis and monitoring of amyloidosis in Crohn's disease.