Renal amyloidosis can be classified based on the extent of glomerular involvement. This classification is similar to the one used for lupus glomerulonephritis.
Amyloid Deposition in the Glomerulus |
Class |
none |
0 |
minimal |
I |
minimal, mesangial |
II |
mesangiocapillary, focal |
III |
mesangiocapillary, diffuse |
IV |
membranous |
V |
advanced |
VI |
Minimal amyloid deposition
glomeruli involved: <= 50%
amyloid deposits within an affected glomerulus: < 10%
amyloid deposits seen on H&E: no
amyloid deposits: focal and segmental within vascular pole and/or mesangium
Minimal mesangial amyloid deposition
glomeruli involved: <= 50%
amyloid deposits within an affected glomerulus: 10-25%
amyloid deposits seen on H&E: yes
amyloid deposits: focal and segmental within vascular pole and/or mesangium
Focal mesangiocapillary amyloid deposition
glomeruli involved: <= 50%
amyloid deposits within an affected glomerulus: 26-50%
amyloid deposits seen on H&E: yes
amyloid deposits: focal and segmental within vascular pole and mesangium.
may have deposits in vessels and the medullary interstitium.
may have minimal tubulointerstitial deposits
should not have diffuse glomerular involvement
Diffuse mesangiocapillary amyloid deposition
EITHER
glomeruli involved <= 50% and amyloid deposition 51-75%
OR
glomeruli involved > 50% and amyloid deposits <= 75%
amyloid deposits seen on H&E: yes
may have significant tubulointerstitial deposits
may have diffuse glomerular deposits within capillaries and/or global glomerular sclerosis
Membranous amyloid deposition
glomerular amyloid deposition: diffuse membranous pattern
mesangial deposits: none or minimal (not prominent)
amyloid deposits seen on H&E: yes
Advanced amyloid deposition
glomeruli involved: > 50%
amyloid deposits within an affected glomerulus: >= 76%
amyloid deposits seen on H&E: yes
may have glomerular amyloid balls
may have global glomerular sclerosis
interstitial inflammation and fibrosis with prominent tubular loss
Conditions that should be classified as Class I:
(1) minimal focal membranous deposition
(2) hereditary amyloidosis without glomerular involvement
(3) renal allograft with tubulointerstitial and/or vascular involvement without glomerular deposits
(4) familial Mediterranean fever (FMF) patient treated with colchicine
Specialty: Nephrology, Clinical Laboratory, Hematology Oncology