Proteinuria in a child with sialidosis: case report and histological studies.

A 9-year-old body with sialidosis had nephrotic-range proteinuria. Histological studies demonstrated massive distension of renal cells, particularly glomerular visceral epithelial cells, by cytoplasmic vesicles which contained material reactive with concanavalin A and wheat-germ agglutinin. In addition, some glomeruli exhibited segmental mesangial thickening or glomerulosclerosis. Ultrastructurally, focal detachment of visceral epithelial cells from the underlying glomerular basement membrane was observed. We postulate that glomerular visceral epithelial cell dysfunction may underlie the proteinuria and focal glomerulosclerosis exhibited by this patient. Hyperfiltration, as suggested by the child's elevated creatinine clearances, may be a contributing factor.