Crescentic Glomerulonephritis Associated With Hypocomplementemic Urticarial Vasculitis Syndrome

Punch biopsy specimen of an urticarial lesion (hematoxylin and eosin stain; original magnification ×400). There is acute venulitis. Neutrophils in this area are conspicuous and show leukocytoclastic changes, but in other regions, the findings are more subtle. Separation of collagen bundles is consistent with edema.

(A) Renal biopsy specimen (hematoxylin and eosin stain; original magnification ×40). Three glomeruli show crescents that are cellular. The interstitium is severely inflamed, and there is obvious tubular loss and fibrosis. (B) A glomerulus (hematoxylin and eosin stain; original magnification ×400) shows a typical lesion. There is proliferation of all elements with relatively little acute inflammation. (C) Glomeruli (immunofluorescence with anti-C1q; original magnification ×400) all showed staining for immunoglobulin G (IgG), IgA, IgM, C1q, C3, C4, κ, λ, and fibrin. The pattern was granular and subendothelial. (D) Electron microscopy shows many large subendothelial electron-dense deposits. No tubuloreticular inclusions are seen.