PMC5858607_01
An electrophoretic analysis of von Willebrand factor (VWF) multimers. The patient's plasma (P) multimer pattern is unusual and characterized by the presence of only a few bands around the corresponding region of smallest VWF protomer (bottom) without the discontinuous multimer pattern proper of pooled normal plasma (NP) VWF.
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A reduced VWF ristocetin cofactor activity (VWF:RCo; <10%, reference range: 50%-150%) was later confirmed, and the multimeric analysis revealed the loss of large- to small-molecular-weight VWF multimers (Figure 1). A subsequent mixing experiment showed that the decline in the VWF:RCo of pooled normal plasma from 99% at baseline to 28% (2-hour incubation at 37 C with a ratio of the patient's plasma to normal plasma of 1:1), suggesting the presence of inhibitors to VWF.
The renal biopsy findings. A light micrograph (A) shows the glomerulus with minor structural abnormalities (periodic acid-Schiff staining). The capillaries are patent, and the basement membranes are delicate. An electron micrograph of a portion of the glomerulus (B) demonstrates scattered segmental subepithelial electron-dense deposits (arrowhead) with distinct but sporadic intervening spikes (arrows), compatible with membranous nephropathy stage I to II. The scale or scale bar is indicated in each panel.
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Finally, his nephrotic syndrome was ascribed to idiopathic membranous nephropathy based on the results of a systemic workup and renal pathologic assessment (Figure 2).