IgA nephropathy classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Ali Poyan Mehr, M.D. [2]; Associate Editor(s)-in-Chief: Olufunmilola Olubukola M.D.[3]
Overview
IgA nephropathy may be classified according to its association to other pathology or by its histological features. When IgA nephropathy occurs in isolation, it is called "primary IgA nephropathy". In converse, if IgA nephropathy is a consequence of a more systemic disease, it is called "secondary IgA nephropathy". Additionally, IgA nephropathy may be histologically classified according to the oxford classification of IgA nephropathy as mesangial hypercellularity, segmental glomerulosclerosis, endocapillary hypercellularity, or tubular atrophy/interstitial fibrosis.
Classification
IgA nephropathy may be classified according to its association to other pathology or by its histological features.
Classification by Associated Pathology
IgA nephropathy may be classified according to its association to other pathology (or lack there of) as follows:
Primary IgA Nephropathy
- When IgA nephropathy occurs alone, it is called "primary IgA nephropathy". It is thus not secondary to any chronic concomitant disease. Before the diagnosis of primary IgA nephropathy is made, secondary causes need to be ruled out.
Secondary IgA Nephropathy
- When IgA nephropathy occurs secondary to other chronic or systemic diseases, it is called “secondary IgA nephropathy”. Secondary causes of IgA nephropathy should be ruled out because secondary causes may alter the management plan and probably the prognosis too.
Classification by Histological Features
The pathologic classification of IgA nephropathy has been developed by the International IgA Nephropathy Network together with the Renal Pathology Society. This classification is called “The Oxford classification of IgA nephropathy”. This classification was done after a 5 years retrospective study on clinical data and kidney biopsies were obtained from 265 patients and multiple pathohistological analyses were done on the kidney specimens [1].
- IgAN is then histologically classified as:
- Mesangial hypercellularity
- Segmental glomerulosclerosis
- Endocapillary hypercellularity
- Tubular atrophy/interstitial fibrosis
| Histological Features | Description |
|---|---|
| Mesangial hypercellularity | In the glomerular mesangium, four or more mesangial cells are noted. |
| Segmental glomerulosclerosis | In the capillary lumen of the glomerulus, a higher density of cells is noted. |
| Endocapillary hypercellularity | Focal and not the whole obliteration of the capillary lumen by matrix material eads to the formation of adhesions or sclerosis. |
| Tubular atrophy/interstitial fibrosis | An estimated percentage of interstitial fibrosis or tubular atrophy is calculated. The more common feature represents the main pathology present. |
References
- ↑ Working Group of the International IgA Nephropathy Network and the Renal Pathology Society. Cattran DC, Coppo R, Cook HT, Feehally J, Roberts IS; et al. (2009). "The Oxford classification of IgA nephropathy: rationale, clinicopathological correlations, and classification". Kidney Int. 76 (5): 534–45. doi:10.1038/ki.2009.243. PMID 19571791.