Comparative Changes Noted in Renal Biopsies on Light Microscopy of ANCA Positive Vs ANCA Negative Serology

Pauci-immune glomerulonephritis is the commonest cause of rapidly progressive glomerulonephritis (RPGN) which is associated with increased mortality and morbidity. More than 90% of these patients have serological presence of either antineutrophil cytoplasmic antibodies (ANCA), of cytoplamic (C) or perinuclear (P) type. "Immunofluoresence studies" exhibiting minimal or no fluorescence is diagnostic in all such cases. The present study aims to study the differences between renal biopsies of serologically ANCA negative versus ANCA positive individuals.

One hundred and twenty renal biopsies (of clinically suspected cases of systemic vasculitis) were sub-divided sub-divided under the heading of serologically ANCA positive and serologically ANCA negative; and scoring them by means of a semi-quantitative scoring system devised at the beginning of the study to identify statistically significant, specific light microscopic features in the sub-components of renal biopsy.

Fifteen parameters were found to be statistically significantly (p-value <0.05) in ANCA positive serological cases. These were glomerular capillary loop infiltration by neutrophils, cellular crescents, fibro-cellular crescents, glomerular fibrinoid necrosis, glomerular sclerosis, peri-glomerular infiltration, interstitial oedema, interstitial eosinophils, tubular atrophy, tubular necrosis, tubulitis, arterial hyalinization, arterial necrosis, arterial vessel wall polymorpho nuclear infiltrate and myointimal hypertrophy.

The presence of above parameters in a renal biopsy report of a patient (in absence of facilities of autoimmune serology and immunofluoresence) can alert both nephrologist and nephropathologist to keep a possibility of renal symptoms arising out of systemic vasculitis.