Standardized Classification and Reporting of Glomerulonephritis

Sanjeev Sethi; Fernando C. Fervenza

Disclosures

Nephrol Dial Transplant. 2019;34(2):193-199. 

In This Article

How Much Scarring has Occurred?

The Answer Lies in Grading the Chronicity in GN

This is an extremely important step in evaluation of the kidney biopsy in every case of GN. Chronic changes are generally irreversible and the extent of chronic changes may be as important as the primary diagnosis and may have an important bearing on the management of GN. Chronic changes are represented in the glomeruli as segmental or global glomerulosclerosis, interstitium as tubular atrophy and interstitial fibrosis and vessels as arteriosclerosis and hyaline arteriolosclerosis. Chronic changes are strong predictors of renal outcomes in glomerular diseases. However, there are only a few diseases that have a scoring system for chronicity, including the Oxford classification for IgA nephropathy,[6,29] the modified International Society of Nephrology/Renal Pathology Society classification for lupus nephritis[30] and the Berden classification for ANCA-associated GN, which is based only on glomerulosclerosis.[31] There are no defined criteria for chronic changes in most other types of GN.

As the next logical step and follow-up to the diagnosis and classification of glomerulosclerosis, a simple scoring system for chronic changes was devised by a group of pathologists and nephrologists.[32] The chronicity grading is assessed on the extent of glomerulosclerosis, tubular atrophy, interstitial fibrosis and arteriosclerosis on a simple sliding scale of 1–10. Global and segmental glomerulosclerosis is scored from 0 to 3, tubular atrophy from 0 to 3, interstitial fibrosis from 0 to 3 and arteriosclerosis from 0 to 1. The scores are then added (total renal chronicity score) to grade the overall severity of the chronic lesions into minimal (0–1 total score), mild (2–4 total score), moderate (5–7 total score) and severe (≥8 total score; Figure 2). This grading system of chronicity is easy to follow and is based on the scoring system used in renal transplant pathology. Clearly the extent of chronic changes may have different significance in terms of treatment and outcomes for the different types of GN. Evidence-based outcome studies are therefore required for the individual disease entities. Although the simple scoring system needs to be validated, it represents a logical, systematic and semiquantitative approach to grading chronic changes on a kidney biopsy. Furthermore, the grading system was recently validated in C3G and we have used it for ANCA-associated GN (manuscript in revision).[33] The chronicity score should be mentioned in the diagnosis or it may be given in the comment section until it is validated for the particular disease entity.

Figure 2.

Schematic shows grading of the chronic changes on kidney biopsy.

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