In the 16 cases with positive glomerular C4d staining, 13 had diffusely granular deposition of C4d along the peripheral capillary loops
and mesangial areas (Figure 2); 2 cases had diffuse granular deposition of C4d in the tubular basement membrane and mesangial matrix but not in the peripheral capillary loops
; and 1 case had focal granular pattern of C4d deposition in the mesangium, peripheral capillaries, and tubular basement membrane.
Caption: The second punch biopsy showed a subepidermal split along with dyskeratotic keratinocytes within the epidermis and widely dilated capillary loops
Diffuse lesions are composed of a widespread increase in eosinophilic material within the mesangium, which stains positive with periodic acid-Schiff (PAS), and uniform widening of the capillary loops.
This lesion is characterized by an accumulation of hyaline, eosinophilic, homogenous material between the endothelial cells and the GBM of the capillary loops.
For each patient we evaluated visibility, course, tortuosity and the possible presence of microhaemorrhages, average calibre of capillary loops
and the number of visible capillary loops
per square millimetre.
Mesangial cells are located between the capillary loops
of the glomerulus and form a support network within the tuft.
At an obvious area of leukoplakia, magnifying narrow-band imaging (NBI) endoscopy showed Type B1 intrapapillary capillary loops
(IPCLs), demonstrating dilatation, tortuosity, caliber change, and distinct morphology [Figure 1]b.
Therefore, it appears that even a single glomerulus with open capillary loops
in the tissue for immunofluorescence (IF) and/ or electron microscopy (EM) is sufficient to evaluate for immune complex deposition.
Electron microscopy disclosed numerous mesangial, epimembranous, and intramembranous dense deposits and large subendothelial deposits in many glomerular capillary loops