Patients with this disease have predominant involvement of glomerular capillaries
, without the granuloma formation seen in Wegener's granulomatosis (WG).
We define segmentally sclerotic glomeruli in tissue sections as glomeruli with open glomerular capillaries
in at least 25% of the glomerular surface area; the remaining area of the glomerulus is obliterated by PAS- and methenamine silver-positive sclerotic material and/or hyalin.
In addition to the thrombi, the glomerular capillaries
showed segmental areas of scarring, adhesion, and hyalinosis.
Mesangiolysis (dissolution and fraying of the matrix) with aneurysmal dilatation of the glomerular capillaries
also may be present.
A description of the changes seen in the glomerular capillaries
and the mesangium should be given, including information on alternations in the glomerular basement membranes, hypercellularity, leukocyte infiltration, matrix expansion, and the presence of deposits or thrombotic changes, among others.
The diabetic changes may be mild (mild global or segmental mesangial sclerosis and hypercellularity; Figure 1, C) or marked (severe mesangial changes, including Kimmelstiel-Wilson mesangial nodules, and thickened glomerular capillaries
without endocapillary cell proliferation; Figure 1, C, inset).
The wall tension in glomerular capillaries
is transmitted to the podocyte cytoskeletal apparatus by cell-matrix contacts, including [[alpha].
Double contours along the glomerular capillaries
are seen commonly on methenamine silver stain (Figure 1, B).