Renal amyloidosis in childhood. An overview of the topic with 25 years experience.

Amyloidosis is a heterogeneous group of diseases characterized by extracellular accumulation of an eosinophilic, hyalin and proteinaceous material containing mucopolysaccharide substance in various tissues and organs. Knowledge about the chemical structure of amyloid fibril proteins has led to the recognition of various forms of amyloidosis including Amyloid-A (AA), Amyloid-L (AL), hereditary, senile, dialysis-related, localized and cerebral amyloidosis. It is now recognized that all types of amyloid contain amyloid P (AP) component which is derived from the serum amyloid P component, a normal circulating glycoprotein and a member of the pentraxin family. A recent classification proposed by WHO-IUIS (Nomenciature Subcommittee) is based on the chemical nature of amyloid fibris rather than their clinical and pathologic features. The kidneys are frequently involved, and renal failure is the major cause of death. Childhood renal amyloidosis is almost always secondary (reactive, AA type) and usually associated with chronic inflammatory, infectious and heredofamilial diseases. In developed countries, rheumatoid arthritis is the most common cause of renal amyloidosis, while in developing countries patients with familial Mediterranean fever (FMF) (untreated) and chronic suppurative infections constitute a large proportion of renal amyloidosis cases. No specific therapy is currently available for amyloidosis. Once renal amyloidosis develops, progress to end-stage renal failure is almost inevitable within 2-13 years. The aim of treatment is to give effective supportive therapy and to control the underlying diseases by colchicine, alkylating agents and appropriate antibiotics. The prognosis of patients with end-stage renal failure can be improved by maintenance dialysis and renal transplantation. The growing knowledge about the pathogenesis and chemical nature of amyloid fibris may open up further avenues for the discovery of specific therapeutic modalities against amyloidosis.