Morphologic and clinical correlates in renal amyloidosis.

Morphologic studies and clinical correlations were undertaken in 59 patients with renal amyloidosis. Spicularly arranged amyloid deposits in the glomerular capillary wall were found in all clinical groups but were more frequent and more extensive in primary amyloidosis and multiple myeloma. The severity of proteinuria correlated with the presence of spicules and podocyte destruction rather than with the amount of amyloid in the glomerulus. The spicules were associated with morphologic and clinical evidence of rapid amyloid deposition and a fulminant clinical course. The absence of spicules and the presence of extensive new basement membrane material may produce basement membrane thickening, lamination, and double capillary wall contours, which are associated with mild proteinuria and, rarely, resolution of amyloidosis. Nodular or mixed nodular-diffuse patterns of glomerular amyloid deposits were more frequent in patients with secondary amyloidosis and a longer clinical course. Renal failure generally corresponded to severe glomerular amyloidosis and tubular atrophy. However, a relatively precipitous, usually irreversible decrease in renal function frequently occurred in patients with renal amyloidosis and did not always have a morphologic explanation. The duration of life from the time of biopsy no death in patients with primary amyloidosis (nine months) was markedly shorter than in those with secondary amyloidosis (more than 50 months).