Histopathologic classification of anti-neutrophil cytoplasmic antibody-associated glomerulonephritis: achievements, limitations, and perspectives

Abstract

Clinical and histological factors have been identified as predictors of early and late renal outcome in ANCA-associated vasculitides (AAV). The presence and severity of kidney involvement at diagnosis are associated with poor prognosis in both patient and renal survival. Histologic findings remain the gold standard for diagnosing patients with AAV. In order to quantify the extent of the morphological parameters in the renal biopsies and to identify the histopathological lesions that predict renal outcome, several scoring systems have been proposed to systematically assess kidney biopsies in AAV. Renal pathologists from an international working group proposed in 2010 a new histopathological classification. This scheme comprises four general categories, based on the predominance of the glomerular histological lesions: focal (≥50% normal glomeruli); crescentic (≥50% glomeruli with cellular crescents); mixed (<50% normal, <50% crescentic, <50% globally sclerotic glomeruli), and sclerotic (≥50% globally sclerotic glomeruli). This article reviews the background and the main studies that have validated the histopathologic classification of ANCA-associated glomerulonephritis, the conclusions derived from these studies, and the perspectives for the assessment of renal outcome in AAV.

Prognostic Factors in Anti-Neutrophil Cytoplasmic Antibody-Associated Glomerulonephritis with Severe Glomerular Sclerosis: A National Registry-Based Cohort Study

“…Generally, the most clinically valuable prognostic models are those that can be used to guide physicians regarding treatment and follow-up regimens for patients [ 31 , 32 ]. If left untreated, a patient with ANCA-GN has a very poor prognosis [ 33 ].…”

Clinicopathological Characteristics and Influencing Factors of Renal Vascular Lesions in Anti-neutrophil Cytoplasmic Autoantibody-Related Renal Vasculitis

“…Kidney disease is common in AAV, and the typical renal presentation is rapidly progressive. Histologically, pauci-immune necrotizing crescentic glomerulonephritis is the most typical pathological characteristic, and histologic findings remain the gold standard for diagnosing patients within ANCA-associated renal vasculitis ( 4 ). Our results found that the more severe the RVLs, the lower the proportion of normal glomeruli, and that the higher the proportion of global glomerulosclerosis, the higher the scores of interstitial fibrosis.…”

“…The kidney is the most common organ involved in AAV, and more than 75% of patients with AAV have renal involvement and missed or delayed diagnosis may endanger the life of a patient ( 1 – 3 ). In 2010, a new histopathological classification was proposed, which included four major categories, foci, mixed, crescent colored, and sclerosis, and provided valuable information to clinicians ( 4 ). However, the classification is based only on glomerular lesions, and parameters of renal interstitial vascular lesions are excluded.…”

Importance of numerical density of tubulointerstitium infiltrates in the prognosis of antineutrophil cytoplasmic antibodies-associated glomerulonephritis

“…Glomerular changes appear in the form of extensive crescent glomerulonephritis, while immunofluorescence microscopy shows a pauci-immune pattern. Pathohistological changes in the glomeruli are classified according to their frequency and extent, crescent count, and the presence of glomerular sclerosis ( 6 , 7 ). Vasculitis is the cause of rapidly progressive glomerulonephritis in about 80% of the cases ( 2 ).…”