Diagnose This! (August 14, 2017)

An immunofluorescence panel for IgA, IgG, IgM, C3, C1q, kappa and lambda was negative. What is your diagnosis?

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The photomicrograph shows a high power image of a glomerulus on Jones silver stain. The glomerulus displays mesangiolysis and enlarged capillary loops often filled with congested red blood cells and frequent fibrin thrombi. While a somewhat similar glomerular appearance can be seen in cryoglobulinemia, in the presence of a negative immunofluorescence panel these findings are most consistent with thrombotic microangiopathy.