[A 21-year-old male patient with nephrotic syndrome and "idiopathic" AA amyloidosis].

A case is reported of a 21 year old man who suffered from Castleman's disease and systemic secondary amyloidosis. He was otherwise healthy until development of a history of edema and nocturia over 3 weeks. Physical examination was normal apart from ankle swelling. Renal biopsy showed amyloid deposits in the glomerulus with gentian violet and congo red. Positive staining by antibody against serum amyloid A protein was demonstrated. Nine months later because of persistent nephrotic syndrome, an abdominal tomography was performed and a mesenteric mass was detected. The patient underwent abdominal surgery. The histopathological examination showed plasma cell variant of Castleman disease and AA amyloidosis in the mass. After the removal of mesenteric mass, the proteinuria gradually decreased and disappeared, and no systemic findings were present.